When VSEL is installed to you system it is scanning file reads and writes on your system.
Disabling the OAS will completely stop that scanning.
Look at configurations options (interface - configure section - On Access Setings)
I would not recommend disabling - but you may want to add exclusions for specific activities
e.g. have a look at https://kb.mcafee.com/corporate/index?page=content&id=PD24880
It would also be strongly recommended to upgrade to VSEL 1.9.2 which has a more comprehensive recommended default exclusion list and resolves a vulnerability