Is 30 mg of Lexapro (escitalopram) a very large dose?

Lexapro (escitalopram) Lexapro (escitalopram) is dosed as 10-20 mg. Daily, and can be lowered to 5mg. In kids or elderly. Few exceptions exist if it is determined by your doctor that response is only partial after sufficient time and no side effects, where higher dose is tried, usually up to 30mg.
Yes. This is a high dose. Your doctor may explain why this is necessary in your case.
Yes. But not unreasonable under certain circumstances. I would consider 40 mg a seriously large dose. That would be roughly equivalent to 80 mg of Prozac and 80 mg of Celexa and possibly to 200 mg of zoloft. Paxil (paroxetine) at 80 mg would be a seriously large dose as well. Most often individual responses determine what is a seriously large dose of medication. All metabolisms are different.