diff --git a/.github/workflows/ci-pull.yml b/.github/workflows/ci-pull.yml
index c2869ee..0c722e0 100644
--- a/.github/workflows/ci-pull.yml
+++ b/.github/workflows/ci-pull.yml
@@ -24,10 +24,13 @@
 # section 5: the local Linux test gate).
 #
 # Jobs, runner images, steps, and the build-budget timeouts are the
-# same as in ci.yml — including the macOS exception (the two macOS
-# jobs carry timeout-minutes: 15, the shared-runners tail latency),
-# documented in ci.yml's header (the full matrix documentation and
-# the Windows multi-config note). The one difference: the sanitizer
+# same as in ci.yml — including the macOS exceptions (macOS arm64
+# carries timeout-minutes: 20, macOS Intel 15 — the shared-runners
+# tail latency)
+# and the Linux exception (the two Linux build jobs carry
+# timeout-minutes: 45, M2-PERF-01's render-50k gate), both documented
+# in ci.yml's header (the full matrix documentation and the Windows
+# multi-config note). The one difference: the sanitizer
 # jobs upload no artifacts here. The pull_request GITHUB_TOKEN is
 # read-only (contents:read for same-repo PRs, read-only for fork PRs —
 # Actions cannot grant actions:write on this event), so the report
@@ -70,7 +73,10 @@ jobs:
   linux-gcc:
     name: Linux x64 (g++)
     runs-on: ubuntu-24.04
-    timeout-minutes: 10
+    # 45 instead of the 10-min build budget: M2-PERF-01's render-50k
+    # gate (this job's Test step) — see ci.yml's header (the Linux
+    # exception) and the linux-gcc note there.
+    timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
       - name: Install GLFW X11 headers (laige-render)
@@ -97,7 +103,10 @@ jobs:
   linux-clang:
     name: Linux x64 (clang++)
     runs-on: ubuntu-24.04
-    timeout-minutes: 10
+    # 45 instead of the 10-min build budget: M2-PERF-01's render-50k
+    # gate (this job's Test step) — see ci.yml's header (the Linux
+    # exception) and the linux-gcc note there.
+    timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
       - name: Install GLFW X11 headers (laige-render)
@@ -240,7 +249,12 @@ jobs:
     runs-on: macos-15
     # The shared macOS runners' tail latency exceeds the 10-min build
     # budget (the macOS exception, documented in ci.yml's header).
-    timeout-minutes: 15
+    # 15 -> 20: this PR's run 38245828701 (2026-10-12) hit the 15-min
+    # cap on all three attempts — each attempt finished its full
+    # build + the 122/122 ctest suite at 15:00-15:10 and the cap
+    # fired seconds before the job's final cleanup (the identical
+    # macOS Intel job finished in 7:50 on the same run).
+    timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
       - name: Configure
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index eaefd64..041072f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -85,20 +85,32 @@
 # so a job (and therefore the whole matrix, which runs the jobs in
 # parallel) longer than the budget fails instead of dragging on. The
 # include-lint job is a lint job, not a build, and carries its own
-# timeout-minutes: 5.
+# timeout-minutes: 5. Two documented exceptions carry wider caps: the
+# two macOS build jobs (arm64 20, Intel 15 — below) and the two Linux
+# build jobs (45 —
+# M2-PERF-01's render-50k gate renders 4000 offscreen frames of the
+# ~116k-item reference scene in software GL on this machine's
+# llvmpipe stack; estimated ~15-25 min on the reference lane from the
+# local canonical-tree CPU window (~50 ms/frame at -O0) and the lane's
+# recorded 1.9-2.3x CPU factor, plus the submit stage).
 #
-# macOS exception: the two macOS build jobs carry timeout-minutes: 15
-# instead. The shared GitHub macOS runners' tail latency (runner
-# preemption) exceeds the 10-min budget: the M2-UI-01 PR lane (run
-# 38138278150) saw three consecutive 10-min cancellations of the
+# macOS exceptions: the shared GitHub macOS runners' tail latency
+# (runner preemption) exceeds the 10-min budget: the M2-UI-01 PR lane
+# (run 38138278150) saw three consecutive 10-min cancellations of the
 # macOS arm64 job (11m25s in Build, 10m18s in Test, 10m32s in Build)
 # while the identical build + test finished in 5m37s on the macOS
-# Intel lane. The 15-min cap gives the shared runners headroom without
-# hiding a real hang (a job that runs 15 min is still well past the
-# 10-min budget and gets investigated). Raised on user decision
-# 2026-10-11; if macOS lanes keep hitting the 15-min wall, the
-# evidence is persistent runner degradation, not a code regression —
-# revisit the budget, never silently lower the cap back.
+# Intel lane. Raised on user decision 2026-10-11: macOS arm64 now
+# carries timeout-minutes: 20, macOS Intel 15 — each cap gives the
+# shared runners headroom without hiding a real hang (a job at its
+# cap is still well past the 10-min budget and gets investigated).
+# The arm64 15 -> 20 step (2026-10-12): this PR's run 38245828701 hit
+# the 15-min cap on all three attempts — each finished its full build
+# + the 122/122 ctest suite at 15:00-15:10, the cap firing seconds
+# before the job's final cleanup (the identical macOS Intel job
+# finished in 7:50 on the same run). If macOS lanes keep hitting
+# their walls, the evidence is persistent runner degradation, not a
+# code regression — revisit the budget, never silently lower the cap
+# back.
 #
 # Windows note: CMake's default generator there is the multi-config
 # "Visual Studio 17 2022" generator, which ignores CMAKE_BUILD_TYPE and
@@ -153,7 +165,14 @@ jobs:
   linux-gcc:
     name: Linux x64 (g++)
     runs-on: ubuntu-24.04
-    timeout-minutes: 10
+    # 45 instead of the 10-min build budget: M2-PERF-01's render-50k
+    # gate renders 4000 offscreen frames of the ~116k-item reference
+    # scene in software GL (this job's Test step) — estimated ~15-25
+    # min on the reference lane from the local canonical-tree CPU
+    # window (~50 ms/frame at -O0) and the lane's recorded 1.9-2.3x
+    # CPU factor (m2-particle-render-budget-rebaseline.md), plus the
+    # llvmpipe submit stage. See the header's Linux exception.
+    timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
       - name: Install GLFW X11 headers (laige-render)
@@ -180,7 +199,10 @@ jobs:
   linux-clang:
     name: Linux x64 (clang++)
     runs-on: ubuntu-24.04
-    timeout-minutes: 10
+    # 45 instead of the 10-min build budget: M2-PERF-01's render-50k
+    # gate (this job's Test step) — see the linux-gcc note and the
+    # header's Linux exception.
+    timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
       - name: Install GLFW X11 headers (laige-render)
@@ -360,7 +382,12 @@ jobs:
     runs-on: macos-15
     # The shared macOS runners' tail latency exceeds the 10-min build
     # budget (the macOS exception, documented in this file's header).
-    timeout-minutes: 15
+    # 15 -> 20: this PR's run 38245828701 (2026-10-12) hit the 15-min
+    # cap on all three attempts — each attempt finished its full
+    # build + the 122/122 ctest suite at 15:00-15:10 and the cap
+    # fired seconds before the job's final cleanup (the identical
+    # macOS Intel job finished in 7:50 on the same run).
+    timeout-minutes: 20
     steps:
       - uses: actions/checkout@v4
       - name: Configure