diff --git a/module/sources/vmware/connection.py b/module/sources/vmware/connection.py
index cde3c53..a62b7fa 100644
--- a/module/sources/vmware/connection.py
+++ b/module/sources/vmware/connection.py
@@ -1326,11 +1326,19 @@ def get_vmware_object_tags(self, obj):
                 log.error(f"Unable to retrieve vCenter tags for '{obj.name}': {e}")
                 return
 
+            # vCenter tags and categories by id: most objects share a few hundred tags, so each
+            # is fetched once per run (per source) instead of once per object it's attached to
+            tag_cache = self.__dict__.setdefault("_tag_cache", dict())
+            tag_category_name_cache = self.__dict__.setdefault("_tag_category_name_cache", dict())
+
             for tag_id in object_tag_ids:
 
                 # noinspection PyBroadException
                 try:
-                    tag = self.tag_session.tagging.Tag.get(tag_id)  # store the object
+                    tag = tag_cache.get(tag_id)
+                    if tag is None:
+                        tag = self.tag_session.tagging.Tag.get(tag_id)  # store the object
+                        tag_cache[tag_id] = tag
                     tag_name = tag.name
                     tag_description = tag.description
                 except Exception as e:
@@ -1341,7 +1349,10 @@ def get_vmware_object_tags(self, obj):
                 if bool(self.settings.tag_name_include_category) is True:
                     # noinspection PyBroadException
                     try:
-                        category_name = self.tag_session.tagging.Category.get(tag.category_id).name
+                        category_name = tag_category_name_cache.get(tag.category_id)
+                        if category_name is None:
+                            category_name = self.tag_session.tagging.Category.get(tag.category_id).name
+                            tag_category_name_cache[tag.category_id] = category_name
                     except Exception as e:
                         log.debug(f"Unable to retrieve category of vCenter tag '{tag_name}': {e}")
 
diff --git a/tests/test_vmware_tag_cache.py b/tests/test_vmware_tag_cache.py
new file mode 100644
index 0000000..3b6cd56
--- /dev/null
+++ b/tests/test_vmware_tag_cache.py
@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+#  Copyright (c) 2020 - 2026 netbox-sync team. All rights reserved.
+#
+#  netbox-sync.py
+#
+#  This work is licensed under the terms of the MIT license.
+#  For a copy, see file LICENSE.txt included in this
+#  repository or visit: <https://opensource.org/licenses/MIT>.
+
+"""
+Most vCenter objects share a few hundred tags, so get_vmware_object_tags() fetches
+each tag and category from the vSphere tagging API once per source, not once per
+object it is attached to. The result must be the same as without the cache.
+
+vcsim serves no tag API, so the tag session is faked.
+"""
+from types import SimpleNamespace
+
+import pytest
+
+from module.sources.vmware import connection as vmware_connection
+from module.sources.vmware.connection import VMWareHandler
+
+
+@pytest.fixture(autouse=True)
+def dynamic_id(monkeypatch):
+    """The vSphere automation SDK is optional and absent here, the tag call needs the type."""
+    monkeypatch.setattr(vmware_connection, "DynamicID",
+                        lambda **kwargs: SimpleNamespace(**kwargs), raising=False)
+
+
+class _CountingTagging:
+    """The parts of the vSphere tagging API get_vmware_object_tags() uses, counting lookups."""
+
+    def __init__(self):
+        self.tag_lookups = 0
+        self.category_lookups = 0
+        tags = {
+            "tag-1": SimpleNamespace(name="prod", description="production", category_id="cat-1"),
+            "tag-2": SimpleNamespace(name="web", description="", category_id="cat-2"),
+        }
+        categories = {"cat-1": "env", "cat-2": "role"}
+        outer = self
+
+        class _Tag:
+            @staticmethod
+            def get(tag_id):
+                outer.tag_lookups += 1
+                return tags[tag_id]
+
+        class _Category:
+            @staticmethod
+            def get(category_id):
+                outer.category_lookups += 1
+                return SimpleNamespace(name=categories[category_id])
+
+        class _TagAssociation:
+            @staticmethod
+            def list_attached_tags(_dynamic_id):
+                return ["tag-1", "tag-2"]
+
+        self.Tag, self.Category, self.TagAssociation = _Tag, _Category, _TagAssociation
+
+
+def _handler(inventory, tagging, include_category):
+    handler = object.__new__(VMWareHandler)
+    handler.inventory = inventory
+    handler.name = "test"
+    handler.source_tag = "Source: test"
+    handler.tag_session = SimpleNamespace(tagging=tagging)
+    handler.settings = SimpleNamespace(tag_name_include_category=include_category)
+    return handler
+
+
+def _collect(handler, moid):
+    obj = SimpleNamespace(name=moid, _wsdlName="VirtualMachine", _moId=moid)
+    return [tag.get_display_name() for tag in handler.get_vmware_object_tags(obj)]
+
+
+@pytest.mark.parametrize("include_category, expected", [
+    (False, ["prod", "web"]),
+    (True, ["env:prod", "role:web"]),
+])
+def test_each_tag_and_category_is_fetched_once(inventory, include_category, expected):
+    tagging = _CountingTagging()
+    handler = _handler(inventory, tagging, include_category)
+
+    results = [_collect(handler, f"vm-{n}") for n in range(5)]
+
+    assert results == [expected] * 5, "the cached tags differ from the fetched ones"
+    assert tagging.tag_lookups == 2, "a tag was fetched more than once"
+    assert tagging.category_lookups == (2 if include_category else 0)
+
+
+def test_cache_is_per_source(inventory):
+    # two sources are two vCenters: tag ids are only unique within one
+    tagging_a, tagging_b = _CountingTagging(), _CountingTagging()
+
+    _collect(_handler(inventory, tagging_a, False), "vm-1")
+    _collect(_handler(inventory, tagging_b, False), "vm-1")
+
+    assert (tagging_a.tag_lookups, tagging_b.tag_lookups) == (2, 2)