We no longer recommend using the spec repo for Cocoapods as, even with our caching, it is overall a slow process and can sometimes be unreliable.
Moving forward, we suggest using Cocoapods 1.8 or newer which allows the use of the CDN, rather than having to clone the entire Specs repo. This will allow you to install pods faster, reducing build times.
Switching to the method is quick and easy and has multiple benefits. Our Cocoapods S3 cache is now deprecated and will no longer be updated.
More information about how to upgrade to Cocoapods 1.8, and how to switch your Podfile to the CDN, please see the following documentation: https://circleci.com/docs/2.0/testing-ios/#optimizing-cocoapods