How to avoid / deal with heavy lore-dumping sessions

So, I don't know if "Heavy lore-dumping sessions" is the right term, hopefully you will understand what I mean.

Also, I am not sure if this is a thing I can avoid at this point, I might have dug myself in too deep.

The thing is, the campaign I am DMing right now has a big city as a main hub the party always come back between quests. At the moment the city is preparing for a big war for which they have a more or less reliable date in which a big battle will happen, so they are making preparations for that day. In the meanwhile the party is tackling quests outside the city to recover some artifacts and become stronger. So the dynamic that we have adopted lately is:

• Party goes out for a number of days in which they travel and do their quest.

• Party come back to big city to decide on big quest and talk to absolutely every contact they have in the city, check in with every faction they know, try to get everyone to do tasks for them while they are out again..

The more or less mandatory session of coming back to the city has become and just RPing for 4-5 hours, informing on what has been happening in the world, how they are training the troops, which troops are moving where and why, how the party has done in their quest outside (which is usually a conversation that repeats 3 or 4 times with different NPCs). I always end exhausted after this session and oh boy I do not look forward to having to run something like this recurrently.

So any fellow DMs out there that have run into similar sessions and have some advice to share? Much apreciated!