Also Windows format artificially limits the partition size to 32GB for efficiency reasons (FAT32 is slower the more free space you have. Solution: fill up that 128GB card and it'll go faster )
I don't remember exactly, just that writing new blocks took a time relative to the number of free block: the more blocks, the longer it took, and that's why Microsoft originally had the 32GB limit: that's about where it started being noticeable. I actually suspect that I'm either wrong/misremembering, or if I'm not that hard drives have gotten fast enough that this "speed limit" is no longer worth thinking about: it's just a useless bit of trivia by now.
Let me see if I can figure out where I heard that from and what it actually means.
edit: well that was easy. Cluster size for FAT32 under 32GB is 16KB. Once it exceeds 32GB it needs to start using 32KB clusters. A lot of tiny files will use a lot more space as a result. A small number of large files wouldn't have the same impact. Nothing to do with speed as I'd thought. I guess I must have heard "efficiency" at some point and equated it with speed, when actually it meant space. Sorry about that.