I'm making my own modpack through the FTB Launcher, and it loads up and runs just fine. The thing is, when I initially load minecraft, it takes absolutely forever. Then, when I play longer than 15 minutes or so, it slows down to a crawl. I usually have 120+ frames a second, but after 15 minutes it's roughly 3-5.
In this next part, pay attention to the log post times on the left side of the picture.
This is the loading log:
Here's during gameplay:
So what am I to do? It seams it's some sort of internet oriented connection error, but I'm not sure.
Here are my system specs:
Model number: HP Pavilion 17-e119wm (slightly modified)
OS: Ubuntu 14.04.01 LTS (64 bit)
CPU: AMD A10-5750M APU x4 (AMD Quad APU @ 2.5-3.5Ghz)
RAM: 8GB ELPIDA PC3L-12800S, 4GB Kingston PC3L-12800S (12GB DDR3 @ 1600Mhz)
GPU: AMD Radeon HD 8650G