If it is any help I have had a response from their tech support - I have copied the details as below.
I have now switched all 3 computers (two laptops one desktop) to the windows essentials security system and they are all running much faster. I have created restore points as I have progressed and will monitor them to see if they are now working as they should - hopefully I will be able to let you know if they have recovered their functionality.
From checking out other forums re the restore point issue there are mixed feelings about how useful they are. All I can say is that they have certainly got me out of a couple of fixes and I would not want to be without the service.
This is what their tech dept said about the slow speed and restore point issue.
Thank you for contacting ZoneAlarm technical support.
I understand that your system runs slow and you have lost restore points after updating ZoneAlarm.
Please download ZoneAlarm Internet Security Suite to your desktop from:
Once this file is saved to your desktop, please go through the information below to remove ZoneAlarm from your computer.
Once ZoneAlarm is removed, please reinstall it from the desktop.
The ZoneAlarm removal instructions are below.
Please download and run the file from the link below to remove ZoneAlarm.
Once ZoneAlarm is removed and you have restarted your computer, please reinstall ZoneAlarm from the link above.
If my answer did not resolve your issue, or you would like further assistance on this issue, please reply to this email. By replying,
and leaving the subject line intact, your response will come directly to me. If you have a separate issue you would like assistance
with, please submit a new request using the website at:
Thank you for choosing ZoneAlarm Security!
ZoneAlarm, A Division of Check Point Software
Hope this info is of some help - I have'nt yet tried their proposed fix as all 3 computers are currently working OK and I am very cautious about spending much more time on the ZA issue.