NDS game file size

I've noticed a lot of game files are about 64 MB. A few, like Pokemon Platinum, are 128 MB, while Pokemon Diamond is 64 MB. Does the game file size mean anything? Can I get a 64 MB version of Platinum? And finally, does the size of the game affect how fast it runs? For example, could I run Pokemon Diamond (64 MB) faster on no$gba 2.6a than I could with Platinum?

The size is the sprites and such used. When a rom is a certain size, it is and you can only trim it! But it saves around 10MB max

Does it affect the speed on NO$GBA 2.6a?

I don't believe so. It's really just amount of data.
IIRC, Platinum had more information/added areas than Diamond/Pearl, which probably accounts for the larger file size.

filesize has no bearing on speed of execution. And no you can't get a particular game into a smaller cartridge size.

So what determines the speed of NO$GBA 2.6a emulation?

the emulator code and how fast your processor is.

What about the amount of RAM on your computer?

if you have a decent amount (2-4GB) it should not have a significant effect.

Hmmm...I have 1 GB of ram, and it says I have an Intel(R) Pentium(R) D CPU 3.00GHz processor. Would this make no$gba laggy and slow?

quite possibly, you have less ram than a computer should these days, and although your processor speed is OK, the pentium D is quite old now.

Doesn't do the video card do much?

on a DS emulator I would say not a lot.