I have a Cirrus Logic 5429 2MB on ISA and it performs quite good in W31/W95. Speed also depends on the CPU used. I've done some benchmarks awhile ago with Winbench 3.11. Tseng Labs ET4000/w32 also had Win GUI accelerator, but I only have an VLB board so I can't do a direct comparison. I also have a CL 5422 1MB but haven't benchmarked it yet.
386DX-40, CL5429 2MB ISA, Win 3.11:
VGA driver: 3.833.328
640x480/8bit: 10.663.156
640x480/16bit: 8.010.081
486DX2-66, CL5429 2MB ISA, Win 3.11:
VGA driver: 3.847.625
640x480/8bit: 24.619.976
640x480/16bit: 20.666.488
800x600/8bit: 21.861.948
800x600/16bit: 8.060.700
486DLC-40, ET4000/w32i 1MB VLB, Win 3.11:
VGA driver: 6.001.725
640x480/8bit: 16.794.357
640x480/16bit: 10.676.952
486DLC-40, CL5429 2MB ISA, Win 3.11:
VGA driver: 5.078.321
Missing 8 and 16-bit color mode because of the wrong drivers at the time. Didn't come around to do it again.
Edit:
Changed the Winbench 3.11 mirror to an anonymous FTP.