Dear Kenichi, Now, I've a tex source file which is written on Microsoft Windows. When I open it with Emacs on my Ubuntu Linux, because the linefeed is different between Windows and Linux/Unix, so the file will have very long lines in it. Even I use the *M-q* and *truncate long line* command, I find the Emacs is always manipulate the file too slowly to tolerate. But I can open it with gedit and edit it very quickly, is there any tricks to solve the problem or some bugs in Emacs? Attached is my tex file. -- Hongyi Zhao 赵弘毅 -- 题目:《春日即事》 作者:吕本中(1084-1145) 病起多情白日迟,强来庭下探花期。 雪消池馆初春后,人倚栏杆欲暮时。 乱蝶狂蜂俱有意,兔葵燕麦自无知。 池边垂柳腰支活,折尽长条为寄谁?