First, is your looping code MUCH faster ?
- and it might be faster if you use Scan Rest and put the seek into additional for.
Just walking the index as you do is often a bit faster than SQL.
Also got top when an index is active is not optimal,
locate is better, if it is needed at all, due to following seek.

>*--- replacement code because can't get the above update statement optimized.
>Set Order To xchange In curaccount
>Go Top In curaccount
>If Seek("Y","curaccount","xchange")
> Do While Not Eof("curaccount") And curaccount.cchanged="Y"
> If Seek("curaccount.clineid","account","clineid")
> Replace cacc With curaccount.cacc, cid With curaccount.cid In account
> Endif
> Skip In curaccount
> Enddo
>Endif