load.php is a critical path that needs to respond as quickly as possible to avoid breaking user experience and given that they are being called a lot (23% of all requests are to load.php = ~2B req/day), this redactions will have a major impact.
Looking at the queries logged by verbose logging:
[x] GuidedTours is making one/two db queries caused by onResourceLoaderGetConfigVars T264817#7601839
[] GrowthExperiments is making several db queries in unloading package files, caused by getSuggestedEditsConfigJson. These need APCu cache: https://performance.wikimedia.org/xhgui/run/symbol?id=61d700876ddcc011535c3a61&symbol=GrowthExperiments%5CHomepageHooks%3A%3AgetSuggestedEditsConfigJson
[] DiscussionTools and Flow are doing something similar to GT in getTermsOfUseMessagesVersion: https://performance.wikimedia.org/xhgui/run/symbol?id=61d700876ddcc011535c3a61&symbol=MediaWiki%5CExtension%5CDiscussionTools%5CData%3A%3AgetTermsOfUseMessagesVersion (but instead of calling Title::exists(), they call Title::getTouched() triggering a db query: https://performance.wikimedia.org/xhgui/run/symbol?id=61d700876ddcc011535c3a61&symbol=Title%3A%3AgetTouched)
[] GrowthExperiments is triggering several queries through HelpPanelHooks https://performance.wikimedia.org/xhgui/run/symbol?id=61d700876ddcc011535c3a61&symbol=GrowthExperiments%5CHelpPanelHooks%3A%3AgetModuleData
[] DiscussionTools is triggering several db queries in load.php due to getting called in [[https://performance.wikimedia.org/xhgui/run/symbol?id=61d700876ddcc011535c3a61&symbol=MediaWiki%5CExtension%5CDiscussionTools%5CHooks%5CHookUtils%3A%3AisAvailableForTitle|HookUtils::isAvailableForTitle]] which sorta doesn't make sense and it seems it's due to the hook handler onParserAfterTidy which gets triggered in every parse including parsing of mediawiki messages (6 of them happen in the load.php I examined) so if this needs to be on parsing of the page, it probably need to hook somewhere else in mediawiki not on ParserAfterTidy