As admin-kun said, your CPU is way to slow to maintain a stable 30FPS in Monster Hunter Tri.
And it gets even worse the further you get in the game, with multiple bosses and a ton of enemies around.
You can try an older build, which might speed up the game a bit for you.
Check out the old gamethread for information regarding that.
These builds are not supported anymore, and you should not ask for support with them.
Any issues, etc, that you encounter with recent builds should be mentioned in the current gamethread.
And it gets even worse the further you get in the game, with multiple bosses and a ton of enemies around.
You can try an older build, which might speed up the game a bit for you.
Check out the old gamethread for information regarding that.
These builds are not supported anymore, and you should not ask for support with them.
Any issues, etc, that you encounter with recent builds should be mentioned in the current gamethread.