If you use windows, click on the battery icon in your task bar, then choose high performance. Next you can divert most ram to java, I can't remember off the back of my head on how to do this, but this is where your old friend google can help. After that, the last thing I did, was in your launcher, the the profile you want to use, then go down to "Use java arguments" at the bottom, now tick that and replace the 1gb with an amount you're happy with (don't use all ram, I would go 1/2gb below the amount of memory you have.