Norton AntiSpam for Outlook - Loads slowly

Norton AntiSpam for Outlook routinely takes about 77 seconds to load when I open outlook. (The second slowest add-in takes about 6 seconds, with a few more at about 1 second each or less)

Consequently I have had Norton AntiSpam disabled for several years, but I am increasingly needing an anti-spam tool.

This problem applies to Outlook 2010, 2013 and 365 - i.e. multiple (re-)installations, multiple versions of Outlook. I am currently using Outlook 365 on a Win7 OS.

Ideas to speed up the loading of Norton AntiSpam would be appreciated.

Thank you in advance