It should improve.

Both Cirrus chips hit the ISA speed limit.
Tridents 8900CL and 8900D can reach that limit, too - but the 8900C is much slower.

5422 additionally supports up to 24-bpp.

The only thing that Tridents have, but Cirruses lack, is register-level CGA and Hercules compatibility modes.

BTW, note that both your Cirrus cards only have 512 KB of RAM - it doesn't make sense!
They are well worth upgrading to full 1 MB.

Grzyb wrote on 2025-05-12, 20:17:

Both Cirrus chips hit the ISA speed limit. […]
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Both Cirrus chips hit the ISA speed limit.

[...]

BTW, note that both your Cirrus cards only have 512 KB of RAM - it doesn't make sense!
They are well worth upgrading to full 1 MB.

Using the Cirrus cards with only 512KB of RAM halves their memory bandwidth. I'm unsure whether they still manage to hit the ISA speed limit that way. An upgrade to 1MB is highly recommended.

The 5420 is 16 bit memory interface, the 5422 can do 32 bit. It's possible the 5420 may gain something from banked 16 bit

Matth79 wrote on 2025-05-12, 21:02:

The 5420 is 16 bit memory interface, the 5422 can do 32 bit. It's possible the 5420 may gain something from banked 16 bit

Well, the data book is confusing there. At some locations, it claims "5420 has a 16-bit memory interface". At other locations, it limits this claim to the "A" revision. The memory configuration appendix B-7 has all configurations that would require 32 bit data bus marked as "5420 rev B only". The clearest indication about a wider memory bus (and not just 16-bit dual-bank operation) is appendix B-5 that describes the 5420-75QC-B, which is clearly described as 32 bit memory path device for 1MB operation. The card of the OP has the 5420-75QC-C (the "C" revision, which is even later), so it will support 32 bit memory access if the 512K were installed.