The previous _skip_gguf_value walked past discarded values with
f.read(n), which allocates and immediately drops a Python bytes
object. For weight GGUFs that carry tokenizer.ggml.tokens (~150K
unicode strings) this wasted ~10 MB of allocation per cold call.
Switch the discard path to f.seek(n, 1). The kernel never has to
copy the bytes into userspace and Python never allocates. Truncation
is now detected on the next read attempt rather than inline (an
out-of-range seek on a regular file is legal and the next read
returns short).
Measured on real downloaded GGUFs (Qwen3.5-4B IQ2_XXS 1.52 GB,
bartowski Qwen3.5-4B IQ2_M 1.70 GB, Qwen3.5-4B-MTP IQ2_M 1.94 GB):
before: 142 ms cold per weight, ~11 MB read
after: 90 ms cold per weight, ~4 MB read
Mmproj reads are unaffected (no tokenizer to skip). Cached re-reads
remain ~50 microseconds. All 161 in-tree backend tests + 85 isolated
sandbox tests pass.
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