Very slow in some cases

For a HTML obtained from http://media.pella.com/professional/adm/Clad-Wood/CRNFMDTR-dl.dxf (~7.5 Mb of text-only) tokenizing takes more than 1 hour.

Preserved file in https://gist.github.com/whalebot-helmsman/987d98c092294aeeafd8735a13a37c32