I've been able to load a set of 135 gpx track files and it works fine. Making visible that many tracks will take OSMAnd awhile to render them the first time and the map will flash while it's happening, but after the first render it all works smoothly.
I don't use the import feature; I have found OSMAnd's import feature lacking.
As of V4.8.6 the OSMAnd import feature only allows
you to import a single GPX file at a time, not a folder of GPX files.
In addition, if you use the OSMAnd import feature you will lose a
track's color and line width and they will be imported with OSMAnd
default values. This is on a Samsung A54 midrange Android phone.
Here's the process I follow:
I do all my trip planning in google maps then use a utility I wrote (
GoogleMapToOSMAndGPX) to
export the GMap data into OSMAnd compatible GPX files. Each track is in a
separate GPX file and all the waypoints are in one GPX file.
So instead of OSMAnd import I just use a file manager app
to copy the entire folder of GPX files to the
Android/media/net.osmand.plus/files/tracks directory. You can also
create folders under the tracks directory to contain these folders. For
example, ...tracks\Germany & ...tracks\Sweden. This type of
organization can make it easier to find and manage these tracks.
To remove the GPX files from OSMAnd you can use a file
manager or OSMAnd My Places to delete individual GPX files or the entire
folder.
NOTE: Starting with Android 11 there are enhanced file
protection protocols put in place that prevent you from accessing the
files in the Android/obb/net.osmand.plus folders. You can change this
location to one that is accessible by other Android applications by going to
settings/OSMAnd settings/Data storage folder and selecting manually
specified /storage/emulated/0/Android/media/net.osmand.plus/files.
Once that's done you can go to My Places/Tracks, navigate to the folder and select "show all tracks on the map". As I said they all show up and work fine.
The nice part is all the track line colors and icon symbols and colors from the google map are preserved/translated and I don't have to do it manually in OSMAnd, although you can if you want.
Hope that helps.