This is an over-simplification. The "fitting in cache" is quite complicated, and as a good rule of thumb exceptions make cache locality less optimal even if you rarely call them. There is little that is "branch-free" about exception code, it literally implies branching.
For performance-sensitive code, I've yet to find a real-world case where exceptions out-perform exception-free code. Nor have I seen much in the way of contrary evidence among people that care about performance.
What's the complication on the fitting in cache? The error handling is taken out of the code that's loaded in icache. When you throw, a runtime library call is made that walks your stack. Until throw, that code has no reason to be in your icache.
For performance-sensitive code, I've yet to find a real-world case where exceptions out-perform exception-free code. Nor have I seen much in the way of contrary evidence among people that care about performance.