One example for the number of increased file operations is creating a new file with filename encryption:
* Windows file systems are file insensitive, but when filename encryption is enabled, the BoxCryptor Drive would be case sensitive (a different capitalization results in different encrypted filenames). In order to stay case insensitive, we have to check all encrypted filenames for all capitalization combinations possible (e.g. abc, Abc, aBc, abC, ABc, etc.) if we want to determine if a file exists.
* This might get even more complicated for nested paths where we have to do this for each element of the path.
--> The result is, that instead of a single CreateFile('X:\path\to\file.txt') operation, we may have to issue many CreateFile operations to get the correct file (the real path could be 'X:\PaTh\tO\FiLE.txt').
This is just one example where you can see, that operations not necessarily have to be the same in unencrypted and encrypted access. Of course, I know that there's still potential for better performance even when using SMB over WAN - and we're working on it, but SMB over WAN is not the best base to add additional layers on top. Plain SMB over WAN already has serious performance issues and problems. (250 MB in 6 hours - that's 11KB/sec on a 10 mbps ?!?! - if I did the math right)