On RunSearchRequest#buildSearchRequestFromCustomField, there is a call to ComponentAccessor.getComponent(SearchRequestFactory.class).createFromParameters(null, getUser(), new ActionParamsImpl(params));.

That createFromParameters method is deprecated on SearchRequestFactory because it's very slow since it ends up calculating the context for the given query.

As we already know, calculating such context is an expensive operation that has a poor performance on large JIRA instances.

We should remove this execution path by crafting the jql query for the custom field case and calling SearchRequestFactory#createFromQuery