A 96K hot cache at MAX_NUM_SEQS=4 left under 100 MiB on 16 GB cards and a mixed prefill step ran out of memory during a soak; 64K keeps the margin and still holds 4 x 32K contexts within 1-5 ms of 4K. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>