diff --git a/datajunction-server/datajunction_server/internal/deployment/fingerprints.py b/datajunction-server/datajunction_server/internal/deployment/fingerprints.py
index b78ad720c..ba4e3e055 100644
--- a/datajunction-server/datajunction_server/internal/deployment/fingerprints.py
+++ b/datajunction-server/datajunction_server/internal/deployment/fingerprints.py
@@ -1,4 +1,5 @@
 import logging
+import time
 from collections.abc import Callable, Iterable
 from heapq import heappop, heappush
 
@@ -289,11 +290,17 @@ async def _load_external_specs(
     parent_cache: ParentCandidateCache,
 ) -> dict[str, NodeSpec]:
     """Transitively load names unresolved within the deployment's own specs."""
+    started = time.perf_counter()
+    db_elapsed = conversion_elapsed = parent_elapsed = 0.0
+    rounds = 0
     known_names = set(known_names)
     external_specs: dict[str, NodeSpec] = {}
     frontier = sorted(set(initial_frontier) - known_names)
+
     while frontier:
+        rounds += 1
         known_names.update(frontier)
+        step_started = time.perf_counter()
         nodes = await Node.get_by_names(
             session,
             frontier,
@@ -305,8 +312,12 @@ async def _load_external_specs(
                 selectinload(Node.owners),
             ],
         )
+        db_elapsed += time.perf_counter() - step_started
+        step_started = time.perf_counter()
         pending = [await node.to_spec(session) for node in nodes]
+        conversion_elapsed += time.perf_counter() - step_started
         external_specs.update({spec.rendered_name: spec for spec in pending})
+        step_started = time.perf_counter()
         candidates: set[str] = set()
         for spec in pending:
             try:
@@ -319,6 +330,20 @@ async def _load_external_specs(
                         exc,
                     )
         frontier = sorted(candidates - known_names)
+        parent_elapsed += time.perf_counter() - step_started
+
+    if rounds:
+        logger.info(
+            "External fingerprint specs: %d nodes in %d rounds; "
+            "db=%0.fms, conversion=%0.fms, parents=%0.fms, total=%0.fms",
+            len(external_specs),
+            rounds,
+            db_elapsed * 1000,
+            conversion_elapsed * 1000,
+            parent_elapsed * 1000,
+            (time.perf_counter() - started) * 1000,
+        )
+
     return external_specs
 
 
@@ -389,6 +414,7 @@ def _compute_merkle_fingerprints(
     shared_fingerprints: dict[int, SemanticFingerprintValue] | None = None,
 ) -> FingerprintMap:
     """`shared_fingerprints` is a cache keyed by id(spec), shared across snapshots."""
+    started = time.perf_counter()
     parent_cache = parent_cache if parent_cache is not None else {}
     shared_fingerprints = shared_fingerprints if shared_fingerprints is not None else {}
     names_to_process = sorted(specs) if only_names is None else sorted(only_names)
@@ -433,6 +459,7 @@ def _compute_merkle_fingerprints(
             if name not in ignored_parse_errors:
                 logger.warning("Fingerprint unavailable for %s: %s", name, exc)
 
+    graph_elapsed = time.perf_counter() - started
     components = strongly_connected_components(graph)
     component_by_name = {
         name: component_index
@@ -465,6 +492,7 @@ def _compute_merkle_fingerprints(
         if remaining == 0:
             heappush(ready, component_index)
 
+    scc_elapsed = time.perf_counter() - started - graph_elapsed
     processed = 0
     while ready:
         component_index = heappop(ready)
@@ -555,6 +583,16 @@ def _compute_merkle_fingerprints(
     if processed != len(components):  # pragma: no cover
         raise RuntimeError("SCC condensation graph contains a cycle")
 
+    logger.info(
+        "Semantic fingerprint graph: %d nodes, %d cached, %d components; "
+        "parents=%0.fms, components=%0.fms, hashing=%0.fms",
+        len(names_to_process),
+        len(cached_results),
+        len(components),
+        graph_elapsed * 1000,
+        scc_elapsed * 1000,
+        (time.perf_counter() - started - graph_elapsed - scc_elapsed) * 1000,
+    )
     return {
         name: component_results[component_by_name[name]][name]
         for name in names_to_process
@@ -637,6 +675,8 @@ async def build_deployment_fingerprints(
     pre_parsed_queries: dict[str, ReusableQuery] | None = None,
 ) -> tuple[FingerprintMap, FingerprintMap]:
     """`only_proposed_names` limits which nodes get a fresh proposed hash."""
+    started = time.perf_counter()
+    timings: dict[str, float] = {}
     proposed_specs = list(proposed_specs)
     additional_target_names = set(additional_target_names)
     deleted_names = {spec.rendered_name for spec in deleted_specs}
@@ -652,11 +692,13 @@ async def build_deployment_fingerprints(
         deleted_names,
         unchanged_names,
     )
+    timings["setup"] = time.perf_counter() - started
     target_specs: dict[str, NodeSpec] = {}
     target_names_to_load = (
         additional_target_names - existing_specs.keys() - submitted_names
     )
     if target_names_to_load:
+        step_started = time.perf_counter()
         target_nodes = await Node.get_by_names(
             session,
             sorted(target_names_to_load),
@@ -668,11 +710,15 @@ async def build_deployment_fingerprints(
                 selectinload(Node.owners),
             ],
         )
+        timings["target_db"] = time.perf_counter() - step_started
+        step_started = time.perf_counter()
         target_specs = {
             spec.rendered_name: spec
             for spec in [await node.to_spec(session) for node in target_nodes]
         }
+        timings["target_to_spec"] = time.perf_counter() - step_started
 
+    step_started = time.perf_counter()
     parent_cache: ParentCandidateCache = {}
     # Reuse ASTs propagate_impact already parsed.
     current_seed_specs = {**existing_specs, **target_specs}
@@ -693,6 +739,8 @@ async def build_deployment_fingerprints(
         proposed,
         parent_cache,
     )
+    timings["ancestor_closure"] = time.perf_counter() - step_started
+    step_started = time.perf_counter()
     external = await _load_external_specs(
         session,
         current_unresolved | proposed_unresolved,
@@ -700,13 +748,10 @@ async def build_deployment_fingerprints(
         ignored_parse_errors=deleted_names,
         parent_cache=parent_cache,
     )
-    # target_specs need a separate copy per side so the id()-keyed
-    # shared_fingerprints cache can't cross-reuse a stale ancestor chain.
+    timings["external_load"] = time.perf_counter() - step_started
+    step_started = time.perf_counter()
     current_external = {**external, **target_specs}
-    proposed_external = {
-        **external,
-        **{name: spec.model_copy(deep=True) for name, spec in target_specs.items()},
-    }
+    proposed_external = {**external, **target_specs}
     shared_fingerprints: dict[int, SemanticFingerprintValue] = {}
     current_graph = SemanticFingerprintGraph(
         {**current_external, **existing_specs},
@@ -721,9 +766,30 @@ async def build_deployment_fingerprints(
         version=version,
         shared_fingerprints=shared_fingerprints,
     )
+    timings["snapshot_setup"] = time.perf_counter() - step_started
+    step_started = time.perf_counter()
     # unchanged_names gives no-op nodes a current fingerprint to fall back on.
     current = current_graph.fingerprints(
         deleted_names | additional_target_names | unchanged_names,
     )
+    timings["current_hashes"] = time.perf_counter() - step_started
+    # The shared cache is keyed only by spec identity. A target can keep the
+    # same spec object but have a new hash when its proposed ancestors change,
+    # so evict its current hash before evaluating the proposed graph.
+    for spec in target_specs.values():
+        shared_fingerprints.pop(id(spec), None)
+    step_started = time.perf_counter()
     proposed_hashes = proposed_graph.fingerprints(proposed_target_names)
+    timings["proposed_hashes"] = time.perf_counter() - step_started
+    logger.info(
+        "Deployment fingerprints: %d targets (%d loaded), %d external ancestors; "
+        "total=%.0fms, %s",
+        len(additional_target_names),
+        len(target_specs),
+        len(external),
+        (time.perf_counter() - started) * 1000,
+        ", ".join(
+            f"{name}={elapsed * 1000:.0f}ms" for name, elapsed in timings.items()
+        ),
+    )
     return current, proposed_hashes
diff --git a/datajunction-server/datajunction_server/semantic_fingerprints/v1.py b/datajunction-server/datajunction_server/semantic_fingerprints/v1.py
index 58ddcdc9b..1704e533b 100644
--- a/datajunction-server/datajunction_server/semantic_fingerprints/v1.py
+++ b/datajunction-server/datajunction_server/semantic_fingerprints/v1.py
@@ -69,6 +69,12 @@ def build_fingerprint(
     """Build a version 1 semantic fingerprint."""
     fingerprint_fields = semantic_fields(type(spec))
     rendered = spec.rendered_spec()
+    # rendered_spec() reconstructs the model and drops private attributes.
+    # Both specs have the same rendered query, so reuse its parsed AST across
+    # current and proposed fingerprints instead of parsing each copy again.
+    if rendered.rendered_query is not None:
+        rendered._query_ast = spec.query_ast
+
     fields = {
         field: normalize_field(
             rendered,
diff --git a/datajunction-server/tests/internal/deployment/fingerprints_test.py b/datajunction-server/tests/internal/deployment/fingerprints_test.py
index 65a254d72..74dca8cb3 100644
--- a/datajunction-server/tests/internal/deployment/fingerprints_test.py
+++ b/datajunction-server/tests/internal/deployment/fingerprints_test.py
@@ -30,7 +30,11 @@
     UNKNOWN_SEMANTIC_FINGERPRINT,
     SemanticFingerprint,
 )
-from datajunction_server.semantic_fingerprints.engine import local_node_fingerprint
+from datajunction_server.semantic_fingerprints.engine import (
+    compose_node_fingerprint,
+    local_node_fingerprint,
+)
+from datajunction_server.sql.parsing.backends.antlr4 import parse
 
 
 def source_spec(
@@ -594,6 +598,42 @@ async def test_build_deployment_fingerprints_only_proposed_names_reuses_unchange
     assert scoped == {downstream.rendered_name: full[downstream.rendered_name]}
 
 
+@pytest.mark.asyncio
+async def test_external_target_is_rehashed_when_its_ancestor_changes():
+    """An external target needs separate current and proposed graph hashes."""
+    current_source = source_spec("source", table="before")
+    proposed_source = source_spec("source", table="after")
+    downstream = transform_spec(
+        "downstream",
+        "SELECT * FROM ns.source",
+        namespace="other",
+    )
+    node = MagicMock()
+    node.to_spec = AsyncMock(return_value=downstream)
+
+    with patch(
+        "datajunction_server.internal.deployment.fingerprints.Node.get_by_names",
+        AsyncMock(return_value=[node]),
+    ):
+        current, proposed = await build_deployment_fingerprints(
+            MagicMock(),
+            {current_source.rendered_name: current_source},
+            [proposed_source],
+            [],
+            additional_target_names=[downstream.rendered_name],
+        )
+
+    expected_current = SemanticFingerprintGraph(
+        spec_map(current_source, downstream),
+    ).fingerprint(downstream.rendered_name)
+    expected_proposed = SemanticFingerprintGraph(
+        spec_map(proposed_source, downstream),
+    ).fingerprint(downstream.rendered_name)
+    assert current[downstream.rendered_name] == expected_current
+    assert proposed[downstream.rendered_name] == expected_proposed
+    assert expected_current != expected_proposed
+
+
 @pytest.mark.asyncio
 async def test_build_deployment_fingerprints_without_external_parents():
     source = source_spec("source", table="table")
@@ -808,3 +848,21 @@ def test_semantic_fingerprint_graph_caches_whole_graph_result():
     # A subsequent scoped call also reuses the already-cached result.
     scoped = graph.fingerprints({transform.rendered_name})
     assert scoped[transform.rendered_name] == first[transform.rendered_name]
+
+
+def test_fingerprinting_reuses_parsed_query_across_rendered_copies():
+    metric = MetricSpec(
+        namespace="ns",
+        name="metric",
+        query="SELECT COUNT(*) FROM ${prefix}source",
+    )
+
+    with patch(
+        "datajunction_server.sql.parsing.backends.antlr4.parse",
+        wraps=parse,
+    ) as parse_query:
+        first = compose_node_fingerprint(metric, parent_fingerprints=[])
+        second = compose_node_fingerprint(metric, parent_fingerprints=[])
+
+    assert first == second
+    assert parse_query.call_count == 1