## Release notes - The related [merge request](https://gitlab.com/gitlab-org/gitlab-runner/-/merge_requests/2358) that addresses this issue disables transport-layer compression in gitlab-runner cache_client.go ## Summary Well, perhaps not a strict bug, but definitely a major performance degradation that seems unnecessary :-) I have been trying to diagnose slow cache operations, and after hacking the gitlab-runner-helper binaries with more timing information I found that the download part of the cache_extractor operations can be extremely slow. This appears to be do to a combination of small buffers and the Golang built-in version of http not being optimized for bandwidth. ## Steps to reproduce - Add timing operations around the io.Copy() operation in routine download() of commands/helpers/cache_extractor.go. - Use a local S3 server, without SSL (to enable highest-possible performance). - When downloading a 931MB cache file with the 'mc' client outside of gitlab-runner, it takes 1.9seconds (10Gb network), so network and S3 server setup is A-OK. ## Actual behavior - Gitlab-runner takes 42 seconds to download the same file. ## Expected behavior - When I hack the code to use the Minio Golang package instead of presigned URLs + HTTP, the download takes 1.9 seconds in gitlab-runner too. ## Environment description - Using our own runners in a k8s cluster - Ceph-backed radosgw S3 storage in the same cluster - No SSL to improve bandwidth ### Used GitLab Runner version 13.1.0 (development) ## Possible fixes If there's interest, we could probably provide a MR to use Minio instead, although there could be some extra complications to handle GCS natively too.