For text-only elements this consumes time, eg. pasting a 1MB-text-file, 1 min./PC-GHz.
A tentative remedy for large MB-text, is to use--
1. a contentEditable HTML-area (for text),
2. an onpaste-event surrogate, and,
3. a dummy-wrapper:
eg:
<CITE>
<DIV id=prepTextarea contentEditable
onpaste='var spot=document.selection.createRange();spot.text=clipboardData.getData("text");return false'
style=PADDING:2;WIDTH:384;HEIGHT:40;BORDER:0;FONT-SIZE:16px;COLOR:white;BACKGROUND-COLOR:maroon;OVERFLOW-Y:scroll;WORD-WRAP:BREAK-WORD;OVERFLOW-X:hidden;CURSOR:text; etc.>
<XMP>pretext before using</XMP>
</DIV>
</CITE>
Here the <CITE> dummy-wrapper tells Microsoft to 'play-IBM' and jumper the delay.
Alternative dummy-wrappers include <LISTING> which is fastest and cleanest-looking (compresses internal margin) but deprecated... etc.
STATUS: TENTATIVE
PROBLEMS: onpaste must wait for clipBoard to fill from source (else it pastes the prior value, as happens on large-MB text).
BENEFITS: zowie-fast: 3 sec. instead of 1 min. on MB-text.