My main database I was trying it on has 147,106 items in 435 Gb.
But I just tried it instead on my Global Inbox which has only 8,206 items in 1.6 Gb and it is still extraordinarily slow to load the “Get Item” step in the shortcut.
In every other respect performance of DTTG is terrific - even on my huge 435 Gb database I can search and view items and resolve item links immediately. Performance only fails with Shortcuts.
Does my sample Create DT3 Item shortcut work for you?