PC very slow since 'Zen' upgrade

Hello Martin,
We are sorry to know that your computer has slowed down after upgrading to Zen version of AVG. Please do not worry, we suggest you to check if you have optimized your computer completely using the AVG PC TuneUp which is installed in your computer. If you have not yet optimized your computer, please optimize and check.
Thank you.

Hello Martin,
We are sorry to know that your computer has slowed down after upgrading to Zen version of AVG. Please do not worry, we suggest you to check if you have optimized your computer completely using the AVG PC TuneUp which is installed in your computer. If you have not yet optimized your computer, please optimize and check.
Thank you.

I've used AVG security for years but since upgrading to 'Zen' my PC has been very slow and occasionally freezes.  Any ideas/advice