if we are talking about the same Globalize Extension here (the
"string".t one, not the one that goes _("string") ) - I found that it
doesn't cache Strings that don't exist in the database (or have a
'text' column that IS NULL). but when it has found them, then it uses
the cache. you could try out some script/console magic to set all the
translations in the default language to the value in the tr_key-column
an see if this speeds up things.
hope this helps,