Hi.
I usually open images, from the gallery view, in a new tab using the mouse wheel button and browse through galleries using the right and left buttons in the keyboard. The fact is that I'm quite fast browsing, not only in this site but any site on the internet.
It seems in the last days the margin for opening new pages has narrowed a lot and I'm being redirected to the captcha every few minutes, and to make it worse, when it happens, the pages i have opened in background demand the captcha too. And many times, after writing the captcha, it takes me to the gallery index and not to my original destination (don't know why, some timeout maybe?)
I can see, that the limitation had good effects in the overall performance, and that only made things worse for me, because now pages open so fast that i continuously hit the limit

.
I totally agree to the need to protect the page against abuse, I have not complained until now, and tried to adapt, but in the last few days navigation became pretty uncomfortable. It will probably not be a problem in a mobile device but with a PC it is.
Could you make the time between requests longer? This way, pauses in navigation could lower the calculated average... or consider something like "invisible recaptcha" maybe...