ADPro: Turning-off Re-linking in DirSync (4331793)

We are experiencing a long DirSync time interval (over 5 hours to completion, typically) and they want to shrink that down as much as possible. The partner has already been advised to make sure all matching attributes, and the attributes used specifically by DirSync, are indexed in AD. After reviewing the logs, the customer wants to turn-off re-linking to save sync time but doesn't know if that will cause problems with previous /future sync or if it will really reduce the DirSync interval.

Although re-linking is supposed to help with performance, in this particular case their customer has 3,000 users in the Source, but 170,000 users to match against in the target.

QUESTION -  With all of that in mind, should we disable the re-link checking and would their be negative side effects that we should warn them about beyond sync times?

The initial sync will take time regardless of re-linking.  Once the initial sync has completed the deltas should not reflect any significant time and if it is taking a significant amount of time then the interval should be shortened. 

Re-linking really comes into play when profiles are reset or re-pull has been issued, since these actions remove data from SQL and result is full synchronization.