Speed optimization of site on Bitriks

MIXTOOLS.RU
You need to understand what is the problem of the brakes of the website, to identify all the causes, to ensure that they do not appear in the future to eliminate them.
Information is transmitted from 1C, I assume that the brakes due to the large number of properties, but in any online store thousands of properties, so you need to solve this problem.

The website on Bitrix. THE PRICE IS NEGOTIABLE.