Experiencing performance issues with Minecraft 1.5? Don't worry, you aren't the only one. Today the Pre-release for Minecraft 1.5.1 is available to download from Mojang, and includes a few notable fixes. Firstly it improves the performance by using a rendering engine from an older Minecraft 1.5 snapshot. It also fixes a few important bugs like crashing under Mac OS X, being able to place paintings, and falling blocks causing problems. The release itself will make an appearance on Launchers everywhere this Thursday. Read the source link for more information and the download.Source: Mojang