This is my experience also. Basically the only workable languages for serious systems programming are C and Go.
In many ways Go vastly improves on C but my Go programs are consistently between 1.5 and 5 times slower than equivalent C programs.
One way to see Go's speed disadvantage is to solve problems on leetcode using both idiomatic C and idiomatic Go. Leetcode tells you the runtime of your solutions for large test sets.
I solved 50 random problems on leetcode in both languages, doing the best I could to avoid writing slow code, and Go is slower by a factor of 1.5 to 5, usually around a factor of 2.
I wish this wasn't the case. I really prefer to use Go.
