Is the logging level the same between the two Runtime Resources? I imagine you would have noticed this already if it were the case, but maybe verify that the same stages are being logged in UAT and Prod by comparing the logs. It's not a huge performance decrease, but if the logging were set to Log all Stages or something like that for the Prod Runtime Resource, that could account for it running slower.
Others have made some good suggestions as well, so I won't list everything again, but one other thing to consider is whether the shared drive being written to is the same between the two environments, assuming it's not writing locally.
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Dave Morris
Cano Ai
Atlanta, GA
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Dave Morris, 3Ci at Southern Company