Issue #3113971 by Spokje, mondrake, acbramley, phenaproxima, andypost, murilohp, mpdonadio, ravi.shankar, pavnish, pifagor, vladbo, JeroenT, voleger, Taran2L: Replace REQUEST_TIME in services

Issue #3351004 by Natallia: Deprecations for PHP 8.1 get_class() and get_called_class() without argument

Issue #3086307 by alexpott, shaal, tstoeckler, mglaman, Berdir, andypost, chr.fritsch, borisson_: Improve installer performance by ~20% by rebuilding the router after the entire installation is complete rather than after each module

Issue #3138718 by sja112, longwave, dww, xjm, alexpott: Convert British English spellings to American English, for the umpteenth time

Issue #2488350 by alexpott, Wim Leers, Dimiter, catch, dawehner, Berdir, webchick: Switch to a memory cache backend during installation

Issue #2659940 by almaudoh, alexpott, phenaproxima, Jo Fitzgerald, markcarver, oriol_e9g, dawehner, dsnopek, jibran, larowlan: Extension System, Part III: ThemeExtensionList and ThemeEngineExtensionList

Issue #2208429 by dawehner, almaudoh, alexpott, jibran, Xano, donquixote, amitgoyal, bircher, stefan.r, Mile23, alvar0hurtad0, Berdir, andypost, larowlan: Extension System, Part III: ExtensionList, ModuleExtensionList and ProfileExtensionList