The fees are so high, this is terrible:
https://bitcoinfees.net/Total mempool transactions:
111,140When is it going to go down back to 2,000 - 4,000 ??
Its not possible to measure when the things will be normal but still the answer for your question can be, Mempool gets less number of transactions only when the price of bitcoin gets stable for few days, either increase or decrease in the price is going to be a cause for more people to buy or sell their coins.