Webmaster in a Nutshell, Second Edition

Keep Content as Small as Possible

The network doesn’t know or care what type of content you are serving. Bits are bits. Size is all that really matters for network transfer time. Keeping file size down also means that your server can handle more requests. The following table shows the theoretical limits for the number of HTTP requests your server can process based on network connection and average file size. In the real world, the numbers will be considerably less, depending on a number of factors.

Connection	Average File Size (KB)
	1K	10K	100K
14,400 bits/sec	1.8	0.2	0.0
28,800 bits/sec	3.6	0.3	0.0
56 Kbits/sec	7.0	0.7	0.1
64 Kbits/sec	8.0	0.8	0.1
128 Kbits/sec	16.0	1.6	0.2
1.5 Mbits/sec	187.5	18.7	1.8
10 Mbits/sec	1250.0	125	12.5
45 Mbits/sec	5625	562	56.2
100 Mbits/sec	12500	1250	125.0
155 Mbits/sec	19375	1937	193
622 Mbits/sec	77750	7775	777.0

The basic performance principle is therefore to send fewer bits and make fewer requests. Try to think of size in terms of download time rather than absolute bits because how short a time a human being has to wait is the ultimate measure of success. If most of your users are on 28.8 modems, make a rule that no image can be larger than 10 seconds. Ten seconds is about 35K if the 28.8 modem is running perfectly.

A slight amount of waste is intrinsic to HTML because HTML is written in ASCII text. ASCII is defined as using only 7 bits of each byte, so 1 bit in 8, or 12.5%, is wasted. A larger waste is due to the fact that text is highly compressible, ...