Perhaps you can upgrade your RAM. But don't use more than 32 MB with your L2 cache configuration.
Thanks for the feedback. If I come across a nice pair of 2x 8MB, I might. I think 16MB would be ample amount here.
But for the record I ran a max allowed amount of 64MB (2x 32MB FPM) in this system and the only trouble associated with it found was incorrectly detected negative value in Norton SI. Neither MEMMAKER nor games were confused by it.
Despite the cacheable amount I also did not notice any performance problems in that scenario.
September 2023 update:
RAM is upgraded to a single 32MB FPM module (Texas Instruments TMS417400ADJ-60)
Bus frequency increased to 40MHz, the CPU runs as DX4-120 now. With two VLB cards I am not seeing any instability.
With the new specs Duke Nukem 3D should be playable but I ran into a stuttering problem discussed in 2016 when using DreamBlaster S2 regardless of audio quality, screen size or detail settings. This post by user orcish75 suggested Duke3D is faster in Windows 95 than in DOS and yes that fixed it. The game runs well in 320x200 with SB16 sound and DreamBlaster MIDI with reported FPS of 20-30.
So the system runs Windows 95 OSR1 now (the one without Internet Explorer, USB, etc.) and I also tested some Windows games:
Breakthru! (Spectrum HoloByte, 1994)
Lode Runner: The Legend Returns (Sierra, 1994)
3-D Ultra Pinball (Sierra, 1995)
Aladdin95 (East Point Software, 1995)
All running well.
Trident 9440AGi even has a Windows95 driver that claims some acceleration.
NSSI for the new config
CACHECHK v7 by Ray Van Tassle: 123.3 MB/s, 51.5 MB/s, 29.8MB/s
Doom fullscreen (from DOSBENCH pack) is 1710 realtics = 43.6FPS.
Hi. Yes, that's the one, ver. 1.4. You are right, 133 does indeed work at normal speed. Did turbo function work for you though? Lack thereof was the deal-breaker for me as I mentioned in the op. If you know how to make turbo work with this bios, please let me know.