We have seen gathers taking 2hrs drop to less then 30mins after the virus scan is disabled for the repository.
Disable the virus scan on the repository.
This may greatly reduce the time it takes to preform the gathering job.
Please be sure you are only running a gather to the repository and not to the database, as gathering directly to the database can take a long time and is not suggested. See InTrust_BestPractices.pdf that's in the documentation folder of your InTrust install.