SQL Server Error 833 On LDF File
Error 833 is not an 'error' per-se. It is reported because your IO subsystem is slow. the size of the LDF has probably nothing to do with it. It can be caused by many factors:


an inherently slow drive
a flaky hardware that masks errors with many retries (typical of consumer grade drives)
the drive is experience more load that it can bear


You need to investigate by looking at the drive load (Perfmon Physical Disk Object), at any OS reported errors for it (Event Viewer), check the drive SMART status. Also investigate the SQL IO load and how much goes to the problem drive, see sys.dm_io_virtual_file_stats