Would the number of volumes and/or connections to a member affect the length of time it takes for a controller failover to be successful when upgrading the firmware?

Reason I ask is this . . .

I have a PS6500M populated with 2TB drives. It hosts 138 volumes and lists 426 connections.

When I upgraded from 4.1.2 (?) to the current 5.0.4 it took nearly 12 minutes before connections were re-established . . . and this caused massive issues with our servers (all of which had been configured according to best practices documents, and all confirmed again after the disruption).

I have been advised by Dell Support to upgrade to the latest and greatest to resolve another issue I am having. However, basically turning off my company to upgrade firmware is going to get me in trouble . . . as is cratering 80+ servers if the firmware takes a noticeable fraction of an hour again.