i like MPLAB X waaaaaaaaay better
altough intellisense is hard to beat, and frankly the autocomplete in netbeans is very basic.
on the subject of compilers, have you tried comparing the binary before and after?
To be frank i would be surprised if you noticed the difference.
First, with PICs there's not much you can do anyway, except perhaps more use of the INDF registers for pointers, arrays and such. In the past there was the nasty habit of multiple MOV or other crap like that, the famous """"added bloat"""", which is not there anymore. Now they try to kill the performance of builtin math as much as possible, but other than that the comparison between my code with free optimization (or level "1" in XC8 2.0, which mimics -O1) and pro optimization was always of a couple RAM locations and a handful of instructions at most.
That can't make that much of a difference, if i'm trying to squeeze every possible byte out of a PIC16/18 i use assembly.
Also because the architecture is what it is.
For AVR i have no idea as the only ones i care about are ATSAM, but have you ever actually used more optimizations than -O1? there nasty things start to happen because the compiler things he's too smart.. or better put you are letting him being too smart. and debugging start becoming a nightmare.