Windows Search was indexing my whole NAS over Wi-Fi, and my laptop ran hot for months

Published Nov 15, 2026, 1:30 PM EST Maker, meme-r, and unabashed geek, Joe has been writing about technology since starting his career in 2018 at KnowTechie. He's covered everything from Apple to apps and crowdfunding and loves getting to the bottom of complicated topics. In that time, he's also written for SlashGear and numerous corporate clients before finding his home at XDA in the spring of 2023. He was the kid who took apart every toy to see how it worked, even if it didn't exactly go back together afterward. That's given him a solid background for explaining how complex systems work together, and he promises he's gotten better at the putting things back together stage since then. My laptop spent the better part of several months running warmer than it had any right to. The fan spun up with nothing open, the palm rest was toasty on the couch, and the battery life slid from days to less than one without me really noticing. I blamed browser tabs and the usual group of battery drains, and moved on. Then I opened Task Manager while the laptop sat idle and found Microsoft Windows Search Indexer near the top of the list. That's the process behind the Search bar on your Taskbar working, and it was busy reading files that weren't on the laptop at all. They lived on my NAS, and my laptop spent its idle time indexing things that already had their own index. Nothing about it looked like a search problem Heat, fan noise, and reduced battery life all pointed at hardware first Laptops run warm for plenty of boring reasons, and none of them involve search. A dusty fan, a laptop stuck on Best performance, or a driver pinning a core would all produce the same symptoms. I checked those first, and they were all fine, which is about as annoying as diagnostics get. Task Manager was more useful once I knew what to look for. Windows Search runs as three processes, and each one does a different job. SearchIndexer.exe owns the database and decides what to read next, SearchFilterHost.exe pulls text out of documents, and SearchProtocolHost.exe opens each location it's told to crawl. When the protocol host is busy, the indexer is reading somewhere specific, and that's all the clues you need. I'm not alone in getting caught out by this. One Microsoft Q&A poster blamed the indexer and Defender for 55% CPU, a loud fan, and worse battery life on light workloads. Another watched it sit at 50 to 55% as a baseline. The forum answer is usually to disable search, which treats the symptom and ignores what the indexer is actually chewing on. The indexed-item count gave the game away Windows tells you how big the index is if you look. Head to Settings -> Privacy & security -> Searching Windows, and the Indexed figure shows how many items it's tracking. Mine had over 700,000, and still has over 350,000 after removing the network drive from the list. For context, Microsoft's Windows Search performance guide says a typical user indexes fewer than 30,000 items, a power user up to 300,000, and performance problems can start above 400,000. The hard ceiling is about a million. The database itself tells the same story. It lives in C:\ProgramData\Microsoft\Search\Data\Applications\Windows, and Microsoft says to check the Size on disk of Windows.db rather than the Size column, which can be misleading. The same guide puts a healthy index at around 10% of the content it covers. Mine was just under a gigabyte, which is a lot of index for a laptop with a few hundred MB of my own files. Windows doesn't index a NAS by default Open Indexing Options and try to add a mapped drive, and you'll find it isn't offered. Windows Search indexes local storage, and a share on a NAS doesn't count. That's deliberate, and it's sensible. Crawling a remote file system on every change would hammer the network and the server. But there's always a way to do something silly on Windows. Right-click a network folder, pick Always available offline, and Windows copies it into the Offline Files cache at C:\Windows\CSC so you can work without the NAS. Microsoft's own documentation on what Windows Search includes in the index is clear about what happens next: offline files in the client-side cache are indexed locally. So one right-click meant copying the share over Wi-Fi, indexing every file in the copy, and keeping both in sync from then on. The worst part is that this is the advice people get. Ask how to search a NAS from File Explorer, and answers on Microsoft Q&A and plenty of third-party guides suggest exactly this. The Offline Files cache can grow to a quarter of the drive by default, too, so it's not a small ask on a laptop SSD. The feature only exists on Pro, Enterprise, and Education editions, but most enthusiast laptops run one of those. Libraries and Enhanced mode are the other ways in Offline Files isn't the only route, just the likeliest. Libraries are another. Try adding a NAS folder to the Pictures library, and Windows refuses because the location isn't indexed. A TrueNAS forum user hit that wall and noticed the Always available offline option sitting right there as a workaround. You can see how that ends. Enhanced mode is the other one to check. Classic indexes your user folders, but Enhanced indexes the whole PC, and anything that looks local, the offline cache included, gets swept up. On managed machines, Group Policy can also push network paths into the index, though that's more of an IT problem than a home lab one. The indexer hides its worst work from you Here's why it took me so long to notice. The Windows Search performance guide explains that indexing slows down while you're using the machine and can pause on battery. That's polite, but it means the heavy lifting happens when the laptop is idle and plugged in, exactly when you're not watching Task Manager. So I'd come back to a warm laptop and a busy fan, with nothing open and no obvious culprit. Add the Wi-Fi radio pulling files from the NAS in the background, and you get a machine that never quite rests. Kicking the NAS out of the index took five minutes Removing the location and rebuilding fixed it without turning search off Disabling Search completely feels like a loss. It's useful to me, especially when I'm in my Outlook inbox. Fixing the indexing issue is simple once you know where to look. Sync Center lives in the old Control Panel, and you'll want to select Manage offline files, then Disable offline files, and reboot your computer. Then search for Advanced indexing options, click Advanced, then Rebuild to get a smaller index. That prevents the issue from ever happening again, but what if you want to keep offline files but not have them indexed? You can use Group Policy to achieve this. The setting is called Prevent indexing files in offline files cache, and it lives under Computer Configuration, Administrative Templates, Windows Components, Search. reg.exe add "HKLM\SOFTWARE\Policies\Microsoft\Windows\Windows Search" /v PreventIndexingOfflineFiles /t REG_DWORD /d 1 /f You can also use the registry. Run the command above in an elevated terminal, then reboot. That will let you keep on using offline files, but they won't be indexed. My laptop finally gets to rest The real lesson is that the index belongs where the files live. Synology's Universal Search indexes shared folders on the NAS itself, and QNAP has Qsirch for the same job, so your laptop asks the NAS instead of copying it. If you'd rather stay on the Windows side, voidtools' Everything can index network folders on a rescan schedule you control, which is a far gentler deal than Offline Files. Sure, Offline Files has its place, especially if you genuinely need NAS files on a plane. But it was never meant to be a search feature, and treating it like one cost me months of a hot laptop. If yours runs warm at idle, open Searching Windows and check that indexed number. If it's in the six figures, the culprit might not be on your laptop at all.