When a sharing violation happens on a network file, then the Server service on the remote machine will detect the sharing violation, but instead of failing right away, then it retries to open the file with certain intervals.
This retry mechanism is quite nice when using programs in a network environment, which haven't been made to handle sharing violation, as it will lower the "visible" sharing violations. If the programs trying to access the same file is already capable of handling the sharing violation, with their own retry mechanism, then this change in behavior with network files might interfere, and lower performance.
Note it is strange that Microsoft have implemented this polling strategy, incase several programs are trying to request the same file, then one or more programs might experience that they never gets access because between each delay another program "steals" the access.
[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \LanmanServer \Parameters]
SharingViolationDelay = 200 (Default = 200 ms)
SharingViolationRetries = 5 (Default = 5)
More Info MS KB150384
More Info MS KB889588