Callum Watson

Contrary to Kumasasa's request, I installed the latest development version of java, java 8, and found all the performance problems vanish. The cpu is still fairly high but the RAM stays low, and my fps stuck to vsync even whilst loading worlds.

Uploaded a forced crash

RAM upon 1.6.2 startup: 240640k
After creating a world and leaving after 5 mins: 511228k - Slight Lag
Creation of a second world and leaving after 5 mins: 755,224k - Major Lag
Creation of a third world and leaving after 5 mins: 1063,384k - Unplayable Lag
Creation of a fourth world and leaving after 5 mins: 1370028k - The memory limit is default, 1024MB

CPU usage upon startup: 20-50% (1.3Ghz dual core, javaw.exe usage)
In-game: 70-95%

Old Usage using the 1.5.2 and lower launcher w/ 1.5.2: 10% on menu, 40% in-game

Evidently the memory leak isn't fixed in 1.6.2

Windows 7 will have asked for permission for the new launcher to be able to access the internet the first time you ran it. If you didn't give it permission then it is the same as you saying that the application is not allowed internet access, in doing this you have denied the launcher access to a file that it requires. I've had the same problem with my friend and the LAN update, he didn't provide permission so we couldn't play together on LAN until the new launcher cam along and he could provide permission. Unfortunately, I don't know how to fix the problem.