The new Minecraft Launcher 0.5 for the latest developer snapshots (found here) appears to be getting “stuck” in memory even after closing the application down. Note the “javaw.exe” processes. These are instances of the launcher left behind, like unwanted leftovers in the refrigerator!
Even powerful rigs with lots of memory will choke and sputter along with a few of these instances running in the background so here’s what you can do on Windows PC’s to shut the launcher down for good (at least until this bug is fixed!):
1) Click the Start button
2) in the command/Search bar, type: taskmgr
3) Choose the Processes tab and look for “javaw.exe” entries
4) Highlight these and click the End Process button
That’s all there is to it!