Follows-up on last year's T159911. This year, specifically focussing on:
* deprecating and/or removing unused/unmaintained modules.
* reducing overhead on startup registry where possible.
See also "Size of scripts" at <https://www.mediawiki.org/wiki/Wikimedia_Performance_Team/Page_load_performance>.
### Progress
* [ ] Reduce amount of `mw.config.set` bloat in startup module from TMH. – {T60082}
* [ ] Reduce mw.config.set overhead in startup from MobileFrontend. – {T186062}
* [ ] Reduce number of Wikibase modules. – T203696
* [ ] Reduce number of MobileFrontend modules. – T194098
* [ ] Reduce number of CX modules. – T203695
* [x] {icon check, color=green} Combine misc `mediawiki.special.*` modules. (Removed 8 modules)
* [x] {icon check, color=green} Reduce number of UploadWizard modules. – @matmarex (Removed 31 of 37 modules)
* [ ] {icon clock-o} Reduce number of `mediawiki.api` modules. (Deprecated 10 modules) – To be removed in #mw-1.33-release
* [x] {icon check, color=green} Removed `jquery.farbtastic` module.
* [x] {icon check, color=green} Removed obsolete `dom-level2-shim`.
* [x] {icon check, color=green} Removed obsolete `es5-shim`.
* [x] {icon check, color=green} Removed obsolete `json` shim.
* [x] {icon check, color=green} Combined `mediawiki.debug` internals. (Removed 1 module)
* [x] {icon check, color=green} Removed obsolete `jquery.expandableField`.
* [x] {icon check, color=green} Combined WikiLove internals. (Removed 1 module)
* [x] {icon check, color=green} Remove `jquery.localize` module. – <https://gerrit.wikimedia.org/r/456303>
* [ ] Remove number of QuickSurvey modules. – {T213459}
* [ ] …
#### Startup response size breakdown
>>! @Catrope and @Krinkle wrote for T192623 (as of 7 May 2018)
>
> Network transfer: 29 K
> Uncompressed content-length: 85,299
>
> Breakdown:
> * mwPerf + mwNow + isCompatible + nojs/NORLQ handling + startUp.addSource: 1,195 bytes (1.4%)
> * startUp.register: 67,999 bytes (80%)
> ** `jquery.*`: !!3013 bytes!!
> ** `mediawiki.*`: !!8532 bytes!! (core modules) {icon exclamation-triangle}
> *** `mediawiki.widgets.*`: 1042 bytes
> ** `oojs*`: 1073 bytes
> ** `skins.*`: 344 bytes
> ** `schema.*`: 2464 bytes
> ** `ext.*`: 51,857 bytes (Extension modules)
> *** CentralNotice: 1125 bytes
> *** VE+Citoid: !!2912 bytes!!
> *** `mobile.*` + Minerva: !!3588 bytes!!
> *** Echo+Thanks: 862 bytes
> *** RelatedArticles+RevisionSlider+TwoColConflict: !!1786 bytes!!
> *** ULS: 912 bytes
> *** ContentTranslation (CX): !!6573 bytes!! {icon exclamation-triangle} T203695
> *** Wikibase: !!14,007 bytes!! {icon exclamation-triangle} T203696
> *** Gadgets: !!4956 bytes!!
> *** TMH/mwEmbed: 1426 bytes
> * startUp.config: 15,537 bytes (18%)
> * RLQ handling + addScript: 485 (0.6%)
>