For comparison, this would achieve the same thing now and is much shorter and more memorable:

  <!doctype html>
  <title></title>
  <h1></h1>

(My recollection is that the HTML 4.01 Strict DTD doesn’t trigger quirks mode; if that’s correct, then it should be precisely the same, except for whitespace variation and the actual doctype node. Also neither is valid, because the title element can’t be empty.)

This is the shortest thing starting with that doctype that I can get validator.w3.org to accept without error or warning:

    <!doctype html><html lang=""><meta charset="UTF-8"><title>x</title>

The ="" there is unnecessary; writing an attribute name only implies an empty value.

If you’re going for shortest valid document at all, <!doctype html> is enough, provided the document exists in a context that makes title optional (e.g. email or <iframe srcdoc>) and that the charset is declared out-of-band.

You may be able to use a UTF BOM instead of the meta tag, or I think someone mentioned elsewhere having the server declare the character encoding in a header. I guess it depends on whether you count the header size which is better for golfing.

I fill in the title and h1 elements - this is just the template. And this version is not precisely the same, because it can't have the same timestamp :).

Wow, I haven't seen an HTML 4.01 doctype in ages.

Your boilerplate lacks all the features of this one...