Launching jDownloader captcha’s solver in a Chrome incognito window (easilly adaptable to other browser?). Look in Advanced prefs for “BrowseCaptchaSolver: Browser Commandline” and enter the following =>
[ "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome", "-incognito", "%s" ]
This will fix the issue of insolvable and slow recaptchas (maybe some kind of conflict between your google id and the process of solving captchas).
The same should work without jDownloader: just solve your captcha in a incognito window.