UploadWizard uses MediaInfo's statements widgets, which render some wikibase properties for which the label needs to be fetched from the API.
On MediaInfo's image page, these API calls are optimized away by fetching then on the server and pre-populating the formatValue cache (see MediaInfoEntityStatementsView::getFormatValueCache & .wbmi-entityview-statementsGroup's data-formatvalue attribute)

We should similarly speed up these API calls in UploadWizard.
I can think of 2 ways:

• let MediaInfo generate these & expose to JS (since it makes the statements module available to UploadWizard, might as well stuff that in MediaInfo as well...)
• or, as soon as UploadWizard detects that MediaInfo is installed, it could fire off those formatValue calls already - they'll be resolved & in cache by the time we hit the metadata step...