Looks like the only place I can find reference to this is in the original release notes for VSM 7.0. It also includes an interesting caveat that may be of help to you (emphasis mine):
During normal SASD operations, SASD enforces a limit of 48 panes of video. However, during Unattended Mode operation, there is no limit enforced on the number of panes. If more than 48 panes are displayed, SASD performance can be poor and, in unusual cases, can crash. See defect number CSCub06627 for related information.
Now, I can't guarantee that things haven't changed in subsequent builds of SASD since the official 7.0 release, but it may be worth a try if you haven't already.
Bulletproof Solutions Inc.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...