File handling is only faster if you need to perform more than one operation on the same file.
For example,
/write on its own would be faster than /fopen | /fwrite | /fclose, but if you need to do more than one /write on the same file, you'd be better off using file handling commands or /filter
However you need to consider when to open and close the file handle. If you don't close the file handle when mIRC exits (be it manually or because it crashed or something), there's a chance your file will be corrupted. This is why it's not really safe to keep a file handle open for too long; in case mIRC crashes.
