Three real differences, not folklore. The stick's Wi-Fi antenna is smaller and weaker than a phone's, so marginal signal shows up here first. Its memory is limited, and the player app loads the entire visible channel list into that memory before you even start watching, so a large list competes with playback for the same resource. And older Firestick models decode HEVC, a compression format roughly half the bitrate of H.264 for the same quality, less comfortably than newer hardware, so a 4K HEVC channel can stutter while the 1080p version of the same channel plays cleanly.

Yes, past a point. Player apps hold the whole loaded list in memory, and that memory pressure grows with the list size, not with what you're actually watching. Somewhere above roughly 18,000 visible channels, sticks with tighter memory start to destabilize: slower loading, stutters that appear unrelated to any one channel, occasional app closures. Hiding groups you never watch shrinks the list the app actually has to hold, which is a real fix, not just tidying up your menu. It costs a few minutes in settings and it is one of the few changes that helps every app on the stick at once, not just the one you happened to be using when it stuttered.

1. 1Large lists cost memory whether or not you watch those channels
2. 2Hiding unused groups reduces the loaded list size
3. 3Symptom often looks like random buffering, not a channel-count problem

Buffer depth and DNS, in that order. Set the player's buffer to none or minimum, since a deep buffer on a memory-tight device delays playback start and slows recovery from any stall. Point the Firestick at a public DNS resolver to shorten lookups. A wired Ethernet adapter, if you have the port for it, removes Wi-Fi signal entirely as a variable, which is worth testing once before assuming the stick itself is at fault. None of these three changes takes more than a few minutes, and together they cover the settings layer completely, so anything left after trying all three is very likely not a settings problem at all.

Run the same channel on a different device over the same connection, or on the Firestick over a mobile hotspot at the same time of day. If it plays cleanly elsewhere, the stick is the bottleneck: try the memory and buffer fixes above. If it buffers everywhere at the same time of day, that pattern points to provider capacity, and no Firestick setting reaches that layer. Ask what uptime figure the service will name; ours is 99.99%, about 53 minutes of downtime a year. That single comparison test takes about five minutes and saves you from swapping devices or settings when the actual cause was never on your end to begin with.