From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Dmitry Gutov Newsgroups: gmane.emacs.bugs Subject: bug#56682: Fix the long lines font locking related slowdowns Date: Tue, 26 Jul 2022 23:52:35 +0300 Message-ID: <200ec6db-a5fb-4dd1-651c-725408ea6e1a@yandex.ru> References: <837d46mjen.fsf@gnu.org> <8335esjppt.fsf@gnu.org> <837d43j198.fsf@gnu.org> <83y1wjhkkh.fsf@gnu.org> <83wnc3hkdg.fsf@gnu.org> <49df74e5-e16a-a532-98d1-66c6ff1eb6c6@yandex.ru> <83pmhuft5a.fsf@gnu.org> <834jz4drm1.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="19068"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Cc: gerd.moellmann@gmail.com, 56682@debbugs.gnu.org, gregory@heytings.org, monnier@iro.umontreal.ca To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Tue Jul 26 22:53:17 2022 Return-path: Envelope-to: geb-bug-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1oGRYK-0004p0-U1 for geb-bug-gnu-emacs@m.gmane-mx.org; 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Tue, 26 Jul 2022 13:52:37 -0700 (PDT) Content-Language: en-US In-Reply-To: <834jz4drm1.fsf@gnu.org> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:237987 Archived-At: On 26.07.2022 14:45, Eli Zaretskii wrote: >> Perhaps it's due to font-lock logic in that it has to match from the >> beginning of a line (not sure we'd want to abandon that promise, >> though). Or maybe something else. > It isn't font-lock, at least not in all major modes. It's the display > engine itself that sometimes needs to go to the beginning of the line. > When it does, going back gets slower with font-lock than without. > This is why you see slower redisplay when you go deeper into a long > line. Makese sense: the text only has to be fontified once, but all redisplays are slowed down (on master), not just the first one.