Overhead of HTML whitespace indentation

Question

I started wondering what is the overall impact of using whitespaces to indent html documents.

Why not simply use tabs to indent? Wouldn't this be more cost-effective: 1 char (\t) vs. example 4 chars (spaces)?

I did little experimenting by converting an asp.net-page to use tabs and compared sizes of rendered markups. By replacing only one partial view's white space caused a page of 22kb size to be reduced to 19,4kb -> that's 12% reduction. Changing all indentation, page ended up allocating 16,7kb - 24% reduction! (used chrome dev tools and Fiddler for verifying)

Is my reasoning sound? Should tabs be used primary for indentation of HTML? Is there any reason to use spaces(such as compatibility with exotic browsers)?

ps. Stackoverflow seems to use spaces too. Converting SO main page to use tabs gave 9% reduction. Is this valid observation? If so, why haven’t they used tabs?

Answer 1

StackOverflow uses HTTP Compression - when this is turned on, the differences between using spaces versus tabs goes down - a lot.

You need to run your tests against the compressed versions for reliable results.

You do have a point though for the cases when a browser does not support the compression schemes the server supports.