[venom0706]

I have a brand new Lumia 630 with WP 8.1. However, sometimes certain apps and games behave unstable and throw me in the home menu. Is this normal? Thank you.

[Harrie-S]

Basically that is not normal.
In genera
- a soft reset could help
- if the apps which crash are on the SD card move them to the internal memory.
- if the apps are beta this can happen.
-....

[venom0706]

I moved a certain game to the internal memory and that fixed the problem. I t also made the game load faster. However, this is not good, as the internal memory is too low (3 gb free), even without any apps installed.

[Harrie-S]

Which class SD card you have.
Using a class 10 from a good brand SD card may help.

[venom0706]

I am using a Class 6 Samsung SD Card (16 gb). I think it is good enough.

[Harrie-S]

Samsung is a good brand so that's okay.
Class 6 can be used but the reading speed is much lower than the reading speed of class 10 and can induce the problems you have.
So I only can advice you to live with what you have now or update your SD card to a class 10

[Godson Arun Kumar]

Some games and apps are pretty much doing that as in most probability they may not be well enough optimized for low memory devices. I'm a regular user of 'hungry shark evolution' and the game has always been crashing on my 520 past many updates whether it's mounted on Sd card( class 10) or phone. Heck, even doodle jump crashes, but asphalt 8 never crashes, as does dungeon hunter 4 or AOE. So, I guess, this is an app thing. Either the app has to be well optimized for 512 MB RAM devices or the RAM is to be improved and needless to say windows on phones is going the latter way with even the 435 getting 1 GB RAM.