Osmand 2.9.3 slow ("Failed to load 'Qt5Core'")

I am using Osmand~ 2.9.3 on a Fairphone 2 and noticed that navigation and rendering is quite slow compared to my other smartphone (Moto G5 Plus). For instance calculating a ~200km route needs 140 seconds on the FP2 compared to 70 seconds the Osmand+ Play Store version on the Moto G5 Plus (factor 2).

Therefore I did some analysis and found the following error in the log which I think indicates cannot use the optimized native code:

04-07 19:15:07.505 909-935/net.osmand.plus E/OsmAndCore:Android/NativeCore: Failed to load 'Qt5Core'
                                                                            java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader[DexPathList[[zip file "/data/app/net.osmand.plus-2/base.apk"],nativeLibraryDirectories=[/data/app/net.osmand.plus-2/lib/arm, /system/fake-libs, /data/app/net.osmand.plus-2/base.apk!/lib/armeabi-v7a, /system/lib, /vendor/lib]]] couldn't find "libQt5Core.so"
                                                                                at java.lang.Runtime.loadLibrary0(Runtime.java:984)
                                                                                at java.lang.System.loadLibrary(System.java:1562)
                                                                                at net.osmand.core.android.NativeCore.loadNativeLibrary(NativeCore.java:25)
                                                                                at net.osmand.core.android.NativeCore.<clinit>(NativeCore.java:44)
                                                                                at net.osmand.core.android.NativeCore.isAvailable(NativeCore.java:55)
                                                                                at net.osmand.plus.views.corenative.NativeCoreContext.init(NativeCoreContext.java:48)
                                                                                at net.osmand.plus.views.corenative.NativeCoreContext.tryCatchInit(NativeCoreContext.java:37)
                                                                                at net.osmand.plus.AppInitializer.initNativeCore(AppInitializer.java:632)
                                                                                at net.osmand.plus.AppInitializer.startApplicationBackground(AppInitializer.java:527)
                                                                                at net.osmand.plus.AppInitializer.access$300(AppInitializer.java:75)
                                                                                at net.osmand.plus.AppInitializer$9.run(AppInitializer.java:770)

(Full log at https://pastebin.com/raw/TaFcAWTX)