Updated 27/10 @19:35: Our provider has now identified the issue on our server and we are working towards a fix. This may involve some downtime late Tuesday evening/early Wednesday morning.
We are currently investigating an issue with poor website performance since early Saturday morning.
Unfortunately the issue appears to be related to the hardware on which the website runs, which is outside of our control. However we are working with our provider to try and address these issues as soon as possible.
Apologies for any inconvenience caused in the meantime.