(I'm kidding, I understand the slowness is due to the webkit rendering...)
Think about it. It's 2015. My PC has 8 cores running at unimaginable speeds. It has 16 GB of memory. And my text editor couldn't open files over 2097152 bytes.
Am I living on a different planet from everyone else? How can people accept this as a normal situation?
More and more I tend to use software that is either minimalistic or started in another era (Emacs + command line tools). The one exception is the web browser which has to be modern or a bunch of websites won't work.
I don't notice any half second delays though. I used to be an Eclipse user and recall it being much more sluggish.
Sublime Text, whilst not perfect is far better than anything else out there. It doesn't struggle with these files either.
Except on Windows it does struggle, a lot, and others like Notepad++ open large files way faster.
Just checked it again: a 20MB matlab m-file opens instantly in NPP however it takes ST3 about half a minute. Half a minute, seriously? After renaming it to txt to get rid of syntax parsing it takes like a second. Which is still longer than NPP and starts to get seriously annoying with files of hundreds of MB.
Still, it's my go-to editor.