-Upgrade to GMS2. Not sure but I think they might've made some improvements, we can't really complain too much if we're using old software after all. I personally use 1.4.1757 and I can see how much slower it is from
this guy's video.
-Something I read on gmc.yoyogames.com the other day - it will only rebuild the texture pages when you edit a graphics resource, so try to batch graphics edits together and work only on code the rest of the time. You will sit through long compilation times less often.
-For "Target" make sure it's set to "Windows" and not "Windows (YYC)". YYC is for making a final version of your game. "Windows" will compile faster.
-As has already been said, in Preferences uncheck "Enable backup on run/debug/create". Keep "Enable backup on save" checked and remember to save often! (Ctrl+S)
-Use smaller sprites. If you're doing pixel art be sure to upscale the pixel art using code and not inside the image editor!
-Putting audio in "Included Files" and loading the files in-game.
-Putting images in "Included Files" and loading the files in-game.
-Buy a faster PC. Use an SSD drive, upgrade CPU & RAM.
-Remember, the first compile will be slower than subsequent compiles.
-Check "Create textures on demand" in settings - won't help with compile times but should help with the load time of your game if I understand this right.
-Obvious one but be sure you've coded methods to quickly get to the part of the game you want to test (instead of booting up a titlescreen every time). This is all about the time it takes to playtest something after all, compilation time is only one part of that.