The transfer speed can be limited. But it’s unlimited by default.
If you want to limit the speed, press “OPTIONS” button in configuration window of a drive item then you can see the option.
If the file size you want to upload is larger than the cache size, it’s no problem.
But the free space of the cache path must be larger than the file size you want to upload.
Please refer to below.
If you turn “background uploading” off and “on-the-fly” on, a cache is not used while uploading but it’s slower than “background uploading”.
Regards.