Is plot polluting my context?

Question

Bug introduced in 10.0.2 or earlier and fixed in 10.1.0

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Whenever I plot something 3 temporary variables get added to my current context.

Example (fresh Kernel):

Plot[x, {x, -1, 1}];
Names["Global`*"]

Output:

{"x", "$3", "$4", "$5"}

When I do the same thing 100 times it adds 300 temporary vars in total.

Do[Plot[x, {x, -1, 1}], {100}];
Names["Global`*"] // Length

Output:

301

This is probably not a big issue for plots inside a notebook. However, if a function relies on plot (like FindAllCrossings) wouldn't the function pollute it's context if it is called repeatedly?

I wondered if this would slow down calls to other objects in that context (if for example 10000 temporary variables had been added).

So I'd just like to know whether my observations are correct or whether I'm totally on the wrong track here.

Answer 1

Answering to drop this off the list.

This still works in 10.2:

In[18]:= Remove["Global`*"]
Plot[y, {y, -1, 1}];
Names["Global`*"]

Out[20]= {"y"}