check out "chrome://flags" and "chrome://gpu". In flags, you can disable rasterization manually without touching the acceleration settings in Chrome and then verify the result in chrome://gpu.
FYI, I ran some more tests to demonstrate what I was saying before about benefiting from disabling hardware rasterization on older GPUs. In all cases, the CPU is a 4th gen Haswell. For the iGPU, the tests were run on Windows 7. For the 1660, it was run on Windows 10.
iGPU with rasterization enabled:
iGPU with rasterization disabled:
GeForce 1660 with rasterization enabled:
The GTX1660 is about 5 times faster in Chrome than the integrated GPU and about twice as fast as the GCN 1st Gen Radeon HD7770 (the HD7770 test was done with Thorium AVX on a 3rd gen Ivy Bridge though, but that probably doesn't make any difference).
Who said software rendering was dead?