How expensive is 404 (file error)?

Question

I deployed my site to a production server ... When I checked through firebug, I found lot errors 404 not foundin my requests ... Mostly from ajax libraries such as scriptResource.axd files ....

I saw that the download time was longer for all the files that were 404 not found...

• How expensive is error 404 ("File not found")?

• Why is the timeline longer for files with status 404 not found.....

Answer 1

404 . , 404- , , . 404, , . .

Answer 2

, , 404: SQL-, , - , .

( -, " ", , , , "" )