Since about mid day yesterday I started to see very slow response times. Even selecting one variable is taking approximately 10 seconds. Requesting 50 is take minutes and sometime the server returns an an error:
There was an error while running your query. We've logged the error and we'll correct it ASAP. Sorry for the inconvenience.
This is a bit hard to test as there appears to be server side caching so if you request a variable once it will be slow and then fast on subsequent requests.
Here are some examples of links I think will take ~10 seconds to respond: