I don't know. Plus500 like to freeze trading when the price is moving
It is often that exchanges / brokers have 2 types of data: throttled or snapshot one for average traders (like Interactive Brokers or Dukascopy) and a quality one for data broadcasters and big players.
Either Plus500 uses standard API that Gox avails to retail traders (which often breaks at fast price movement) or Plus500 indeed screws its customers (which is typical for bucketshops). Plus500 is a bucketshop.
and 1broker don't seem to be doing it.
1broker does something else - quote from their website:
Quote
Our algorithm uses several data sources to calculate the current price. This protects us and our customers from market manipulations.
1broker manipulates the price (through the algorithm only they know) and then claims to be saving you from manipulation. You can't make this stuff up
