I am trying to load an image, and I am comparing two methods: a plain gdk_pixbuf_new_from_file, and a GdkPixbufLoader with a fread/gdk_pixbuf_loader_write loop. I am very surprised by the difference of efficiency of both methods: with my sample image, on the computer I am using, gdk_pixbuf_new_from_file takes only about 3.5 seconds, while the GdkPixbufLoader method takes about 22 seconds. I understand that keeping track of the current state and keeping the data structure consistent across calls must take some time, but I expected a 10% cost, not a 500% cost! To have things right, here are some details: - There is no swap/out of memory problems, all is well within the cache and free memory limit, and the limiting factor is really CPU. - Almost all the time is spent in gdk_pixbuf_loader_write. In particular, I am not wasting time in the loop system since all the file is read in just 4 big fread. - There is no signal for area-updated; adding a no-op one costs two more seconds. - It is a Gtk+ 2.6.8-1 from Debian, on a Pentium 266. I did not find anything pertinent in the ChangeLog to expect better with 2.8.1. I intended to use a GdkPixbufLoader to do partial rendering while loading a big image, but if it means that the user must wait six times what he would have waited otherwise, it is somewhat defeating the purpose. Did I miss something?
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