Vibrant Visuals: Render thread spike causes severe stutter when swapping items or placing blocks

Short description:

Game freezes for approximately 1 second when swapping hotbar items or placing blocks in Vibrant Visuals mode. Issue does not occur in Simple or Fancy mode.

Steps to reproduce:

1. Set graphics mode to Vibrant Visuals

2. Create any world (tested on flat and normal worlds)

3. Walk around for a few seconds

4. Swap any item in hotbar OR place any block

5. Observe approximately 1 second freeze

6. Immediately swap another item - notice no stutter

7. Walk around again for a few seconds

8. Swap item again - stutter returns

Expected result:

Smooth gameplay without frame drops during item interaction in Vibrant Visuals mode.

Actual result:

Render thread spikes from ~8ms to ~32ms, causing FPS to drop from ~96 to ~1.4 for approximately 1 second. GPU time remains constant at 8.120ms throughout, confirming this is a CPU render thread issue and NOT a GPU shader compilation problem.

Stutter pattern (important):

The stutter does not occur on every single item swap. The pattern is:

- Walk or idle for a few seconds, then swap item = STUTTER occurs

- Immediately swap another item = no stutter (data still cached)

- Walk or idle again for a few seconds, then swap = STUTTER returns

This pattern suggests the deferred rendering pipeline is expiring or evicting render data (G-buffers or draw call cache) after a period of no item interaction, forcing a full rebuild on the next item swap. The longer the idle period between swaps, the more likely stutter will occur.

FPS data captured via in-game debug screen:

Normal gameplay (no item interaction):

- FPS: 96.5

- Render thread: 8.764 ms

- Main thread: 8.044 ms

- GPU Time: 8.120 ms

During item swap or block placement:

- FPS: 1.4

- Render thread: 32.692 ms (4x spike)

- Main thread: 9.157 ms (minimal change)

- GPU Time: 8.120 ms (NO change - confirms GPU is not the bottleneck)

Additional notes:

- This issue has persisted since Vibrant Visuals was first introduced on mobile (tested in Asus ROG 9 pro)

- Tested across multiple Minecraft versions over the past year

- Issue reproduces on both stable and beta versions (latest tested: 1.26.30.21 beta)

- Tested with all graphics settings at minimum (render distance 5 chunks, all effects disabled) - stutter still occurs

- Issue occurs regardless of world type (survival, creative, flat)

- Issue occurs regardless of world complexity or entity count

• Asus ROG Armoury Crate CPU/GPU frequency lock at maximum has no effect on the stutter