Why is Minecraft lagging? [closed]

I bought a new Graphics card and power supply for my computer so that I could run games better. I got it and it works great- I can play games like Skyrim on full graphics with absolutely no lag. However, when I went back to play Minecraft on full-screen with upped settings, it still lags! Why is this, because my computer should be able to run no problem?

My graphics card is a SAPPHIRE HD 7770 GHz Edition 1GB GDDR5

Solution 1:

First off, you should ensure you are running the appropriate Java version. If you are a 64 bit machine then make sure you have the latest 64 bit version. If you are 32 bit then get the latest 32 bit version.

That being said, it's quite possible that you need to allocate Java more memory. Vanilla minecraft should run no problem on the default 1 GB of memory but if you install mods, that quickly becomes too little. If you're on Linux (and probably works on Mac OS too) then simply put the flag '-Xmx2G' into the java command you start minecraft with. This particular flag puts 2 Gigabytes (hence the 2G), if you wanted 3 Gigabytes you would use '-Xmx3G'. If you are on windows, then this guide should help you. If you are running vanilla minecraft and still get low FPS after giving it more memory it would be helpful for you to post your system specs (CPU, memory speed, memory amount, etc) as well as anything else you've tried already.