Not too well, CS:GO can occasionally choke on 4 actual cores nowdays due to more resource intensive sounds (HRTF) and hitbubbles.
I'd probably seek a i7-8700 for just CS:GO. It can suck up to 90% CPU usage even with an overclocked 8700k, but that happens at quite high framerates.
Oh and I consider most CS:GO benchmarks flawed since they use a workshop map - actual 128tick servers are more demanding, especially when teams stack nades etc.