I don't believe the yellow orbs are supposed to give that much XP. They give like 10 times the XP of green orbs in the same zone. In Midtown every group of mobs drops a pile of yellow orbs that give massive amounts of XP lol. And I got so many Omega points too.
The only place where they seem to give the correct XP is the the event quests in ICP. You know, rescue the hostages, etc., where if you have rescued one and someone else rescues another, the XP orbs drop for you? Those give amounts I'd expect.
Also apparently the level 60 zones drop a lot lower XP, too.
Either way, beyond Ant-Man I knocked out Nova, Cable, Black Panther, She-Hulk and Nightcrawler to 60. Huzzah. I will try to get a lot of characters done until they fix the yellow orbs.