Ok, so like you might already be guessing.. it's very likely got something to do with resourcing.. somewhere. Here's a few things you can check on and rule out, or in! Important thing I always mention even though you're doing it already I'd guess: Make sure you have good backups! #2 involves REORG, so it could rearrange things and possibly be a Bad Thing™ but the chances are super low.

Creating Backup:
In SQL Server Management Studio (SSMS), right-click your local database in (localdb)\MSSQLLocalDB, go to "Tasks" > "Back Up...". Choose a destination (e.g., your desktop), and run the backup. This gives you a restore point if anything goes wrong.

SQL Server LocalDB Limitations: LocalDB Constraints: LocalDB is meant for development and testing, not heavy workloads like Azure. With your 500 MB database, 50 tables, 100k+ records in some, and ~1,000 in one, it's probably not hitting that much of a resource limit, but then again you wrote ~1000k which is actually 1 million, and if that's what you truly meant, then yeah it's almost definitely hitting resource limits like RAM and CPU...

1. Local Machine Limits: Your local setup might not be matching Azure’s almighty power. LocalDB depends on your machine’s resources, so if CPU or memory is tied up by other tasks, performance will tank. Check what’s running using something like procexp64 so you can dig in to the tree of processes if you need to (probably will stick out though, if its a problem..).

2. Index and Stats Check: Your indexing and paging are solid, but the imported local database might not have the same optimized stats or indexes. Run these to try and bump things around, you can use REORGANIZE instead of REBUILD to be less "destructive" during testing. Obviously do this in a non-prod environment (if anyone else happens to be reading and having similar issues in prod ;) )

   • Use UPDATE STATISTICS [table_name]; to refresh statistics safely without affecting data.

   • For indexes, use ALTER INDEX ALL ON [table_name] REORGANIZE; (Again, less intrusive than REBUILD and will optimize performance without locking the table.

3. Configuration Differences: Azure almost definitely has some crazy performance tweaks like memory or query settings that aren't even documented (possibly*) and any Special Sauce isn't going to be replicated by LocalDB. Review the compatibility level and settings after importing.

4. Timeout Issues: The TL;DR is that, almost always, timeout errors suggest some kind of resource strain or misconfiguration. LocalDB might have stricter defaults for resources, so try increasing the timeout in your connection string (e.g., Connect Timeout=30) or optimize queries further if it makes sense. For your specific issue I'd guess with that few records, optimizing queries isn't the issue at all.

5. Import Process: The "Import Data-tier Application" method might not carry over Azure’s optimizations. Consider scripting the schema and data from Azure (using "Script Database as" or "Generate Scripts" (can be found in the 2nd screenshot) and loading it into SQL Server Express or Developer Edition locally for better performance.

6. Network Gremlins: So the last thing I'll mention is the ever famous Network Gremlins. They're everywhere. Make sure you don't have a VPN running or installed, like maybe one with a kill switch etc. Also, if you're working remote but also can go to the office, does anything change? If so, try to figure out what's different - It'll either be the work VPN firewall rules, routing, or your home's connection. Use Wireshark to sniff the internet/network adapter, but also sniff localhost adapter 127.0.0.1 - this is my little trick that nobody hardly ever does, and sniffing localhost can tell you a ton of really interesting things. It also works on way more problems than just this one.

Other things you might want to try that are pretty straight forward:

• Switch to a full local instance of SQL Server Express or Developer Edition (it's free for development) and give this a try instead of LocalDB. Install it, restore your database backup, and test performance.

• If you're trapped and being forced against your will to use LocalDB, first - blink twice, then monitor resource usage (CPU, memory, disk I/O) on your local machine during queries and consider upgrading your hardware or killing any processes you can. Re-Nice the LocalDB binaries (procexp64 can set the "nice" by right clicking and Set Priority. Use "High") and if that works, your hardware is probably kinda lackin.

• Check for those network Gremlins and use filters like this one for SQL only: (tcp.port == 1433) || (udp.port == 1433)

• Or this one for the servers you're interested in ONLY (instead of all the background noise):
  ip.addr == server.ip.here

If none of this helps, you might need to share query scripts or logs, anything that can help get you to an answer. Best of luck!