For a while it was processing uploaded logs almost immediately, but it has been backlogged for more than a few days for the past month; here is the latest note from the LoTW homepage:
-- LotW status in www.arrl.org/logbook-of-the-world
will be updated daily to convey information of interest to the user community, including planned downtime and changes that will impact operations. In addition, the state of LotW's processing queue is now updated hourly in www.arrl.org/logbook-queue-status
Updated hardware to improve LoTW's throughput is on order and expected in six to eight weeks. We appreciate the user community's patience while we while work to bring LoTW's performance to an acceptable level.
Harold WJ1B ARRL COO