Build times vastly dirrerent for different architectures

Does anyone have experience of builds on s390 taking considerably longer to run than the equivalent builds on x86 or power? This seems to be the case for the workers we have, but I’d like to know if it something inherent in s390 or if configuration can be done to improve performance.
I’m monitoring an s390 build request queue, not submitting the builds so I don’t know what they are actually doing and don’t have access to the .travis.yml files. What I do have is users complaining that s390 builds are taking too long. Any insights would be greatly appreciated.

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