Effect on Performance

All tests were done on an Acer VI9 motherboard. The ISA bus was set to run one-quarter as fast as the CPU: 40/10 and 33/8.25. Adding a synchronous math co-processor had no effect on these tests. BIOS settings for memory timings were not altered from their power-on defaults. Turbo was disabled. Making those adjustments would improve things, but that is a topic for another page. ISA vid card: "Definicon CAD Race 1024" with 1MB (Tseng ET4000 based)
VLB vid card: "Diamond Stealth 64 DRAM T" with 2MB (S3 Trio64 based)

486DX4-120	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	256	-	Yes	71.4
40	256	Yes	-	45.4

486DX L1 enabled	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	256	-	Yes	28.5
40	256	Yes	-	23.2
33	256	-	Yes	23.2
33	256	Yes	-	19.2

486DX L1 enabled	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	Disabled	-	Yes	26.3
40	Disabled	Yes	-	20.8
33	Disabled	-	Yes	21.7
33	Disabled	Yes	-	17.2

486DLC @	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	256	-	Yes	15.8
40	256	Yes	-	13.8
33	256	-	Yes	12.9
33	256	Yes	-	11.4

386DX @	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	256	-	Yes	14.2
40	256	10	-	12.6
33	256	-	Yes	11.7
33	256	8.25	-	10.5

486DX L1 disabled	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	256	-	Yes	13.1
40	256	Yes	-	11.9
33	256	-	Yes	10.8
33	256	Yes	-	9.9

386DX @	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	Disabled	-	Yes	6.6
40	Disabled	Yes	-	6.2
33	Disabled	-	Yes	5.4
33	Disabled	Yes	-	5.1

486DLC @	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	Disabled	-	Yes	6.2
40	Disabled	Yes	-	5.8
33	Disabled	-	Yes	5.1
33	Disabled	Yes	-	4.7

486DX L1 disabled	L2	ISA card	VLB card	average frames/sec shown by 3DBench
40	Disabled	-	Yes	5.4
40	Disabled	Yes	-	5.1
33	Disabled	-	Yes	4.4
33	Disabled	Yes	-	4.2

Conclusions:
1) The Cyrix 486DLC is designed to operate with functioning L2 and suffers a large perormance hit when L2 is absent.
2) The Intel 486DX is designed only to run with L1 enabled.
3) DX4ODPR chips are cool:-) (OverDrive Processor, Replacement type) With such a CPU, the ISA card seems to be mostly limited by the speed of its own circuitry; still faster CPUs would not help.