Fast way to check if $f(x)>x$ for what value of $x$


In order to find the value $x$ for which $f(x)>x$, I tried it using the following code:

ParallelTable(If(TrueQ(f(x)>x),x,Nothing),{x,0,10^9})

For some function $f(x)$. But it takes forever, is there a way to make it go faster?