title.. used a bunch of extractors (~15) and started extracting some buildings, crashed at about 4 in a row. (multiple times)

Well there's your problem: I don't think you should be using Fifteen extractors at once...

is there a daily cap also for this artifact?

There's no cap, they can be used and are made to be able to use in sequence.

Never knew that. Would come in handy, I guess.

Neither did i, untill i had a planet filled with artis to extract.

Apparently not O_o

I have used many many extractors at a time. 20+ some times. never an issue. sure its not some thing on your end?

sometimes it does cause the game to crash, BUT, the game also keeps track of how many youve used.
its VERY handy if youve stolen someones planet and want to rip off a half dozen storages or other artis, and done really care if you lose the planet afterwards

that it's nice it keeps track how many you used before the crash, it doesn't make having to reload the page and find the planet 10 times over any less annoying

That is not true, you can use them without extracting. I have used multiple extractors at a time without any issue and I have even forgot to use a couple extractors on a planet for months and used some on other planets in the mean time, came back noticed them and extracted some buildings.

Extractors are basically an effect (which is not displayed on your planet's effect's tab), which let you extract up to X times where X is the # of times you used them.

That's what he was saying.

When I tried using more than one about a month ago I got an error message saying that buildings were already eligible for extraction or something.