Our Drupal Content management systems calendar crashes if a lot of customers attempt to access at the same time. It is possible to method to throttle demands towards the calendar to x number each minute etc?

There's a module which will Throttle drupal. It is among the Core modules, actually I believe its known as Throttle.

It may sound like you have to employ using caching. Admin / Configuration / Performance -> Enable CSS/JSS aggregation. Download the Boost module to produce static HTML files from the web site to offer to anonymous customers. I'm not sure anything regarding your site, but when nobody needs to sign in, Boost can help you in a major way.

This will alleviate/help your bottleneck. But we have to learn more to supply better direction.