I have had tv u/s after IVF pregnancy at 6 w 5 days (h/r 110), 7 w 4 days (h/r 130) and 8 w 4 days (h/r 140). The h/r seem slow. Is this a concern?

Normal. While it is understandable to be worried after all you have been through to get pregnant, you are overthinking this one. Try to relax and enjoy your pregnancy and congrats!
No. Who told you that 130-140 is slow? Do not believe them, and if you're getting your info from the internet - do yourself a favor and stop. Normal fhr in the first trimester can be anywhere from about 120-170 or so, and that's all pregnancies not just ivf. Good news!