diff --git a/CHANGELOG.md b/CHANGELOG.md
index 865e4cedd..c9ed84759 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 - Windows: add WER integration for syncing tags and attachments to WER. ([#1837](https://github.com/getsentry/sentry-native/pull/1837))
 - Report `cache_overflow` discards due to `cache_max_items` or `cache_max_size`. ([#1884](https://github.com/getsentry/sentry-native/pull/1884))
+- Crashpad/Windows: optimize scope flushes for crash events and external crash reports. ([#1841](https://github.com/getsentry/sentry-native/pull/1841))
 
 **Fixes**:
 
diff --git a/external/crashpad b/external/crashpad
index a40e3bdc1..7ac234db3 160000
--- a/external/crashpad
+++ b/external/crashpad
@@ -1 +1 @@
-Subproject commit a40e3bdc151f8dcd0bec6d3fb07901d3fa728e49
+Subproject commit 7ac234db350fcea825fd7e4ae680e4ad86191781
diff --git a/src/backends/sentry_backend_crashpad.cpp b/src/backends/sentry_backend_crashpad.cpp
index 61a44a170..71fabc3d7 100644
--- a/src/backends/sentry_backend_crashpad.cpp
+++ b/src/backends/sentry_backend_crashpad.cpp
@@ -214,8 +214,36 @@ crashpad_register_wer_module(
 }
 #endif
 
+static int
+write_attachment(crashpad_state_t *state, const sentry_path_t *path,
+    const char *data, size_t size)
+{
+    if (!path || !state || !state->client) {
+        return 1;
+    }
+    return state->client->WriteAttachment(
+               base::FilePath(SENTRY_PATH_PLATFORM_STR(path)),
+               base::as_bytes(base::make_span(data, size)))
+        ? 0
+        : 1;
+}
+
+static int
+append_attachment(crashpad_state_t *state, const sentry_path_t *path,
+    const char *data, size_t size)
+{
+    if (!path || !state || !state->client) {
+        return 1;
+    }
+    return state->client->AppendAttachment(
+               base::FilePath(SENTRY_PATH_PLATFORM_STR(path)),
+               base::as_bytes(base::make_span(data, size)))
+        ? 0
+        : 1;
+}
+
 static void
-flush_scope_to_event(const sentry_path_t *event_path,
+flush_scope_to_event(crashpad_state_t *state, const sentry_path_t *event_path,
     const sentry_options_t *options, sentry_value_t crash_event)
 {
     SENTRY_WITH_SCOPE (scope) {
@@ -231,7 +259,7 @@ flush_scope_to_event(const sentry_path_t *event_path,
         return;
     }
 
-    int rv = sentry__path_write_buffer(event_path, mpack, mpack_size);
+    int rv = write_attachment(state, event_path, mpack, mpack_size);
     sentry_free(mpack);
 
     if (rv != 0) {
@@ -242,8 +270,9 @@ flush_scope_to_event(const sentry_path_t *event_path,
 // Prepares an envelope with DSN, event ID, and session if available, for an
 // external crash reporter.
 static void
-flush_external_crash_report(
-    const sentry_options_t *options, const sentry_uuid_t *crash_event_id)
+flush_external_crash_report(crashpad_state_t *state,
+    const sentry_path_t *external_report_path, const sentry_options_t *options,
+    const sentry_uuid_t *crash_event_id)
 {
     sentry_envelope_t *envelope = sentry__envelope_new();
     if (!envelope) {
@@ -258,7 +287,13 @@ flush_external_crash_report(
         sentry__envelope_set_header(envelope, "cache_dir",
             sentry_value_new_string(options->run->cache_path->path));
     }
-    sentry__run_write_external(options->run, envelope);
+
+    size_t size = 0;
+    char *serialized = sentry_envelope_serialize(envelope, &size);
+    if (serialized) {
+        write_attachment(state, external_report_path, serialized, size);
+        sentry_free(serialized);
+    }
     sentry_envelope_free(envelope);
 }
 
@@ -334,9 +369,10 @@ crashpad_backend_flush_scope(
     sentry_value_set_by_key(
         event, "level", sentry__value_new_level(SENTRY_LEVEL_FATAL));
 
-    flush_scope_to_event(data->event_path, options, event);
+    flush_scope_to_event(data, data->event_path, options, event);
     if (data->external_report_path) {
-        flush_external_crash_report(options, &data->crash_event_id);
+        flush_external_crash_report(
+            data, data->external_report_path, options, &data->crash_event_id);
     }
     data->scope_flush.store(false, std::memory_order_release);
 #endif
@@ -386,9 +422,10 @@ flush_scope_from_handler(
     }
 
     // now we are the sole flusher and can flush into the crash event
-    flush_scope_to_event(state->event_path, options, crash_event);
+    flush_scope_to_event(state, state->event_path, options, crash_event);
     if (state->external_report_path) {
-        flush_external_crash_report(options, &state->crash_event_id);
+        flush_external_crash_report(state, state->external_report_path, options,
+            &state->crash_event_id);
     }
 }
 
@@ -796,10 +833,17 @@ crashpad_backend_startup(
         sentry_free(filename);
 
         if (data->external_report_path) {
-            crash_reporter = base::FilePath(
-                SENTRY_PATH_PLATFORM_STR(options->external_crash_reporter));
-            crash_envelope = base::FilePath(
-                SENTRY_PATH_PLATFORM_STR(data->external_report_path));
+            if (sentry__path_create_dir_all(options->run->external_path) == 0) {
+                crash_reporter = base::FilePath(
+                    SENTRY_PATH_PLATFORM_STR(options->external_crash_reporter));
+                crash_envelope = base::FilePath(
+                    SENTRY_PATH_PLATFORM_STR(data->external_report_path));
+            } else {
+                SENTRY_ERRORF(
+                    "mkdir failed: \"%s\"", options->run->external_path->path);
+                sentry__path_free(data->external_report_path);
+                data->external_report_path = nullptr;
+            }
         }
     }
 
@@ -968,8 +1012,8 @@ crashpad_backend_add_breadcrumb(sentry_backend_t *backend,
     }
 
     int rv = first_breadcrumb
-        ? sentry__path_write_buffer(breadcrumb_file, mpack, mpack_size)
-        : sentry__path_append_buffer(breadcrumb_file, mpack, mpack_size);
+        ? write_attachment(data, breadcrumb_file, mpack, mpack_size)
+        : append_attachment(data, breadcrumb_file, mpack, mpack_size);
     sentry_free(mpack);
 
     if (rv != 0) {