some queries on standby preventing replication updates

I have a master and a slave database. 

I've got hot_standby_feedback turned on, max_standby_streaming_delay=-1. I've configured the master and slave to keep a few days of WALs around.

I've noticed that when some large queries are run on the standby machine (ones that take more than a minute or so), replication updates are paused. Is there a way to fix this?

Thanks,

Joe