Today I ran two 100 game tournaments at 1m+0.6s time controls of Rustic Alpha 1 against WukongJS 1.4 and 1.5.
The 1.4 version ended up at +130 Elo vs. Rustic A1. Assuming Rustic's 1695 rating, that would put version 1.4 at 1825, which is fairly close to its actual rating in CCRL Blitz.
However... The 1.5 version defeated Rustic A1 with a rating difference of +268 Elo (!). That would mean an improvement of 128 Elo on top of version 1.4. What did you change between 1.4 and 1.5? (I can see in the engine output that 1.5 searches deeper and faster than 1.4; that will at least be part of the difference.)
Against 1.4, Rustic can hold its own up to the late middle game, where WukongJS will start to outmaneuver it, because it's transposition table / move sorting advantage makes it tactically superior; this is even more evident with version 1.5, where that superiority starts much earlier in the game. In the endgame, WukongJS can outmaneuver Rustic by something like 10-12 ply because of the transposition table. I'm curious to see what the TT (and later, move sorting enhancements) will do for Rustic in that regard
Good job on Wukong 1.5. When CCRL tests it, I estimate it will be around 1950 Elo +/- 30 points or thereabouts.
PS: I ran both as UCI engines under CuteChess. No issues in 200 games total.
edit: 1.5 is about 2-3x as fast in nodes/second than version 1.4. I assume that this is caused by that optimization you got e-mailed by someone. I'll have to watch that video sometime.