A 15 second city it seems.
Forest City is essentially a high-end refugee camp for wealthy Chinese trying to escape Xi's government with their assets intact - but recent Chinese crackdowns have completely destroyed their target market. The Malaysian government doesn't want any more Chinese investors coming in but investors from other countries aren't interested in these Chinese-built towers - proximity to Singapore notwithstanding.
It's faster to fly from Kuala Lumpur to Singapore than to cross the bridge from Johor Bahru, anyway.