I have had 4 series of Rituxan infusions over the last 8 years.
The biggest concern and side effect is allergic reaction so the dose you with a big dose of Benadryl. This makes me sleepy/groggy.
The last two rounds I had (Nov 2016) in the morning so I took a nap in the afternoon.
Because of the allergy monitoring the infusion is slow! Usually six hours the first round, 4 hours the second round (if you do 4 it's the first that is longest as well).
I usually bring water, snacks, a blanket, book or reading material becauase it's boring!