Appointments Plus - Response times


We are experiencing high lag/response times for the following functions:-

1. When we select a service and response time is fine, however when we then select a service provider it takes approx 10 seconds to present us with the service provider calendar.
2. If we then click 'next month' it takes approx 10 seconds to display the next months calendar. The same happens when selecting 'previous month' to go back.

So it appears to be the delay when presenting the service provider calendar details.

I can confirm:-

1. We have 'Use Built-in Cache' set to 'Yes' in A+ settings, however we have tested with this set to 'No' with no significant change in response times.
2. Our server ping and response times are fine
3. Our broadband does not have this lag
4. This lag does not occur on other pages/functions of the site

These delays do not happen when 'No preference' is selected for the service provider, and we have no working hours selected for the 'No preference' case, so I can only assume that this happens when the page has to load or check the database for available appointment slots. We currently have 2 service providers and approximately 170 services assigned to each. Our client is finding it difficult to book multiple appointments in succession due to this delay.

Any thoughts on how to improve this would be appreciated.