Waveform compression speedups depend on thread count

The 2024 dictionary-based waveform compressor paper reports 17 GB VCD conversion in 312 s and decompression in 179 s using 12 threads, versus fsdb2 at 1001 s and 1882 s using one thread. Its own single-thread times are 3354 s and 1532 s, so the parallel speedup is not an equal-thread codec comparison. Figure 5 also shows fsdb1 beating the proposed compression ratio on TEST4, while fsdb1 does not preserve glitches and same-timestamp ordering; fsdb2 does. Cite configuration and fidelity with the headline ratios.