thinkorswim slow on old laptop

2 weeks ago, thinkorswim migrated to the version 8 of the oracle JRE.
Since then, the software got terrible slow on my old laptop running linux Mint and using a ATI Radeon HD2400XT card.
Xorg used nearly 100% cpu all the time, and the GUI was not responsive at all.

After some investigation, i discovered that :
- thinkorswim uses JavaFX for the fancy graphics.
- JavaFX on JRE8 has some sort of blacklist for old graphic cards.
- No 3D hardware acceleration  was used.
- Xorg had to render everythink by software.

No the solution was quite simple, just add these options to yourthinkorswim.vmoptions file:
-Dprism.forceGPU=true
This option bypasses the JavaFX blacklist.

I also added other options, don't know if they changed anything... :

-Dsun.java2d.opengl=true
-Dsun.java2d.xrender=true
-Xverify:none -XX:+UseParallelGC
-XX:MaxPermSize=256m

Hope this helps those having the same issue :)