perf: re-enable native-comp JIT and hand GC to gcmh

early-init.el disabled JIT native compilation with (setq native-comp-deferred-compilation nil), the obsolete alias of native-comp-jit-compilation. Despite the comment, setting it nil turns JIT off entirely rather than making it synchronous. Most modules then ran interpreted for the daemon's lifetime, and the native-comp-speed/jobs settings in system-defaults.el were dead. The "Selecting deleted buffer" async race that prompted the disable was an Emacs 28/29 issue. This is 30.2. I re-enabled it with native-comp-jit-compilation t and silent async warnings.

GC was pinned at the stock 800KB: early-init restored it post-startup and the minibuffer setup/exit hooks bounced back to it. That's Emacs's bare-editor default, far too low for 184 packages, so GC pauses fired often during completion, agenda, and LSP/AI work. I replaced both hand-rolled mechanisms with gcmh, which keeps the threshold at 1GB during activity and collects on idle.

Verified a clean full launch in a throwaway daemon (JIT on, gcmh active, no backtrace) and gcmh's threshold cycle in batch.

2 files changed, 0 insertions, 27 deletions

diff --git a/tests/test-system-defaults-functions.el b/tests/test-system-defaults-functions.el
index a5210be01..2562ff6aa 100644
--- a/tests/test-system-defaults-functions.el
+++ b/tests/test-system-defaults-functions.el
@@ -79,20 +79,6 @@
   (should (eq (cj/disabled) nil))
   (should (commandp #'cj/disabled)))
 
-;;; cj/minibuffer-setup-hook / cj/minibuffer-exit-hook
-
-(ert-deftest test-system-defaults-minibuffer-setup-inflates-gc-threshold ()
-  "Normal: entering the minibuffer raises `gc-cons-threshold' to most-positive-fixnum."
-  (let ((gc-cons-threshold 800000))
-    (cj/minibuffer-setup-hook)
-    (should (= gc-cons-threshold most-positive-fixnum))))
-
-(ert-deftest test-system-defaults-minibuffer-exit-restores-gc-threshold ()
-  "Normal: leaving the minibuffer restores `gc-cons-threshold' to 800000."
-  (let ((gc-cons-threshold most-positive-fixnum))
-    (cj/minibuffer-exit-hook)
-    (should (= gc-cons-threshold 800000))))
-
 ;;; unpropertize-kill-ring
 
 (ert-deftest test-system-defaults-unpropertize-kill-ring-strips-properties ()
diff --git a/tests/test-system-defaults.el b/tests/test-system-defaults.el
index 928124f56..f653e1fbb 100644
--- a/tests/test-system-defaults.el
+++ b/tests/test-system-defaults.el
@@ -63,19 +63,6 @@ test clears it first to capture the path derived from the sandbox."
                                  (expand-file-name dir)))
         (should (string-suffix-p "backups" (directory-file-name dir)))))))
 
-;;; minibuffer GC hooks
-
-(ert-deftest test-system-defaults-minibuffer-gc-hooks-registered ()
-  "Normal: the minibuffer GC raise/restore hooks are installed.
-Their bodies are tested in test-system-defaults-functions.el; this asserts
-they are actually wired onto the minibuffer hooks."
-  (test-system-defaults--with-load-environment
-    (let ((minibuffer-setup-hook nil)
-          (minibuffer-exit-hook nil))
-      (test-system-defaults--load)
-      (should (memq 'cj/minibuffer-setup-hook minibuffer-setup-hook))
-      (should (memq 'cj/minibuffer-exit-hook minibuffer-exit-hook)))))
-
 ;;; Customize-save warning
 
 (ert-deftest test-system-defaults-customize-save-warns-once ()