Hyperlinks are colour formatted by the use of two styles 'Hyperlink' and 'FollowedHyperlink' If you modify the styles to reflect the colours you prefer they will be reflected across the document without attempting to format each link.
The speed issue relates to the time taken to update the links. Have you set the Word option > advanced > general > update automatic links on open?

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Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com