Lately i noticed a heavy drop in the download speed. A few weeks ago, the only limit was my own bandwidth (16k down), but now, everything CRAWLS at max. 200 kb/s, mostly barely reaching 100 kb/s.
Is this a problem with my provider or do you experience this too?

i get about 200ishk/s, which is about normal for me, where the hell do you get 16k?

From my provider :) and a few weeks ago, i downloaded everything from GOG at maximum speed, between 1mb/s to 1.5 mb/s. But now ... back to the days of introducing highspeed internet with 100 kb/s from the year 2000.

I have the same problem but it's because my ISP sucks and still hasn't fixed my speed.

I just downloaded Port Royale 2 at an average of 1.4MB/s, so there doesn't appear to be any problem with the servers.

So that GOG and/or the community can better understand your problem it would be helpful to use industry standards in referencing your speeds in relation to your internet connection.
8 bits = 1 Bytes (capital B for bytes, small b for bits)
kb/s = kilo bits per second
kB/s = kilo Bytes per second
When using "Meg" or a million use capital "M" so as not to confuse the unit of measure with "milli" which is denoted by a small "m."
Industry standard for referencing consumer/business internet connection speeds is in bits per second (b/s).
Consumers or Users tend to refer to their download speeds in bytes per second (B/s) since this is the common method that is displayed to them via a web browser.
When you say that your connection is 16k or 16000 DSL this causes confusion because connections are not referenced that way. I assume you mean 16 Meg bits per second (16Mb/s) since you stated earlier that your normal download speeds where 1M to 1.5M (since 16M divided by 8 is 2M - and then accounting for loss in bandwidth for connection protocols (called "overhead") and any loss over the phone lines - which tends to be more prevalent with copper rather than with fiber optics - this would put you roughly in the 1.5MB/s range for "real world" web browser download speeds).
I'm not trying to be "petty" or anything by pointing this out. Again, my goal is to try and help your situation get resolved as soon as possible.

Oh, sry. I assumed, that this was clear enough.
But right now, the problem seems (?) to have solved itself. Download speeds are as usual (around 1.5 megabyte per second). I really have no clue, what was wrong during the last weeks and until now. I changed nothing and i think, the GOG staff did also nothing :)
Maybe if we know, where the servers are located? I see, that Bitgravity is located in California, but i'm not aware about any connection problems from this area to my end of the line.