8× fewer cuBLAS forward passes for validation (2406→301 chunks for 154K
bars). Removed 3 chunk-0 debug syncs that stalled the pipeline. Reduced
per-chunk sync from every chunk to every 10th (301→31 pipeline stalls).
Portfolio features stale for ~8.5h within each chunk — acceptable since
market features (42/48 dims) dominate action selection. Causal
sensitivity analysis confirms portfolio features have <2% importance.
Expected validation: 2.5s → ~0.5-1.0s per epoch.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>