Just wanted to return to my post to explain what eventually fixed this issue.
It turns out that the VIC was running on a VCenter Server, which only had 1 x CPU core and 2gb ram..
Having logged a call with excellent support people at Veeam, they analysed my collector logs and noted that the virtual machine spec may not be up to the job.
So, having increased the virtual hardware spec on the VC VM to 2x CPU Cores and 3gb RAM (after discovering that you need the VC to do this unless you know which ESX host the VC VM is running on!!!!
) all is now much better and the VM is no longer breaching OpenView CPU thresholds.
It is still a very hard working system and even now with 2 Cores (vCPU's), it runs both constantly at over 50% utilization, but looks much healthier than it's previous constant 100%
So many thanks to the support peeps who assisted me in getting to the bottom of this issue and hopefully this forum post may assist others in bottoming out similar issues.
For info, I was unable to figure out the sizing calculators mentioned in a previous post by Gostev.. very confusing - some tech notes may be a good idea for whoever put these together as I couldn't work out how to get it to produce any useful figures or even where I was supposed to be entering our site specific information and numerics.
Many Thanks again,