Thorium results in Mercury benchmarks

The [Mercury benchmarks page](https://thorium.rocks/mercury_performance) has text description of the results copied from the [Thorium benchmarks page](https://thorium.rocks/performance). The screenshots of the results are different, so they may be coming from Mercury or Firefox.

Compare the text on the Mercury benchmarks page with the Thorium benchmarks page, then inspect the repository source for the corresponding page content. Verify which benchmark the screenshots represent and update the Mercury description so it matches those results; confirm the rendered page shows the corrected text.

Written by the indexing model from the issue text.