some people believe the original ibm vga to be the slowest vga card, but i speculate that the chips441/442 may be even slower. they both have 8bit isa bus, but the ibm vga has 32bit dram width while the chips441/442 has 16bit. there are some faster cards with both 8bit isa bus and 16bit dram width such as chips450, realtek3105 and wd90c00, yet they are more optimized and run a higher dram clock at 40-50mhz, while the chips441/442 is a very early vga chipset and goes up to the same 28mhz clock of ibm vga only.
anyway, the chips441/442 is quite rare to find, probably because it was quickly overwhelmed by early svga cards like the oak037, video7 etc.