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?