It should help enormously having the crossing at Enfield unconstrained it is the only crossing point between Maynooth and Killucan which must be about 50km.
The biggest delay problem on the Sligo line is the 17:00 Sligo-Dublin train that causes chaos in leafslip season because it has to cross with about 5 other trains. Since this isn't scheduled to stop at Enfield anyway, I can't see this being much help except that it allows an opportunity to offload the passengers into a bus or a couple of taxis and leave the train at Enfield until the 19:05 down train has passed.
But this will be a help and I must say that Irish Rail seem to have spectacularly gotten their act together on Sligo line delays since Christmas. I have had to alter my route home from the station because the train is routinely 3 or 4 minutes early at Edgeworthstown and so keeps the level crossing closed while it waits for the departure time.