I am going to assume that you are at a lower level in your aiki-jujitsu trainging. This is the reason for your training slow. If your aiki-jujitsu is done well, then your partner gets seriously crunched. You need to really know what you are doing in your aiki-jujitsu to prevent this from happening while moving at a good pace.
Well I have been training for 2 years and am a brown belt (we grade every 4 months). As much as I love the art I can get frustrated by the way my instructors teach. The problem with my club is that it is relatively small but with a wide range of ages and ability. We have teenagers and pensioners and white belts to black. For different reasons my instructors never train that hard. I've been to several seminars where we have trained harder so I know that my experience is not the norm for all Aiki-Jujutsu clubs but the other clubs are too far to travel to regularly and it would end up costing me alot each week in time and petrol (I'm from the UK).
That's not to say the wrist locks aren't applied properly - my wrists get really sore after an evening of Nidan or Shodan and depending on the instructor they can really crank them on! However, whenever we practice otoshi's or Kote-Gaeshi we never really get to practice our ukemi properly. This is more what I am referring to when I say we practice 'light'.
@ JFF here's the website: http://www.aikidocircle.com/aboutus.html
Thank you for all the feedback, I appreciate that Aikido is not taught uniformly from club to club and that finding the right club/dojo/instructor is important. I am not put off by the fact that Aikido may be difficult to pick up initially for the beginner as I feel it is similar for Aiki-Jujutsu (the first grading is purely Sureware waza, which puts many people off who are not interested in the traditional aspect of the art).