@Vlad Hm, it seems that now it works. Yesterday, I couldn't get conversion results quickly without specifying the full currency name.
However I still made a screen recording of "100 USD TO SGD" and "100 us dollar to singapore dollar" for your reference
It seems that the web results for "100 USD TO SGD" have noticeable delay.
But for "100 us dollar to singapore dollar" the web results appear instantly (also the Map appeared)
I also tried it for JPY. The search time seem to have doubled when searching via the currency shorthands.