I sent the logs from both SANs. Primary with 50 volumes and painfully slow and secondary with 5 nodes (not all were added because the primary was unusable).
Firefox and Chrome (both latest with cleared cache) takes around 2 minutes to simply display the 50 volumes in the only volume group.
Any action on those volumes (add,edit,remove) taks the same time.
Internet Explorer is faster with around 1 minute to do the same actions. This is still very slow.
Still, API command volume_status takes around 4 seconds to display the same data.
Other API commands like volume_replication and create_iscsilv are also a lot faster (a couple of seconds instead of a couple of minutes).