FSDB windowing and resident reuse must be separated from reconstruction speed

Measured with documented FsdbReader W-2024.09 APIs on a large RTL dump: fresh open plus hierarchy was about 200 ms, while point-window signal loads were 85–129 ms. Repeating ffrLoadSignals on already resident selections took 0.1–1.2 ms; explicit unload restored loading cost. A clock port and root clock matched all 12.97M timestamp/value records, but full loads cost about 6.9 s versus 0.47 s; point-window port loading fell to about 0.12 s. Independent compiled RTL-derived FIFO and instruction-decode streams matched reader output exactly for the tested records, including unknown bits. Do not identify every derived signal as an internally encoded secondary without documented evidence, or compare evaluator-only timings against reader costs including operand loading. The manual documents complete-flush-session loading even with view windows; this alone is not a profile proving the remaining floor.