diff --git a/src/core/core.cpp b/src/core/core.cpp
index 39eff2ce8..bca66d2dc 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -363,7 +363,9 @@ void Core::process()
         tolerance = 3*CORE_DISCONNECT_TOLERANCE;
     }
 
-    toxTimer->start(qMin(tox_iteration_interval(tox), toxav_do_interval(toxav)));
+    unsigned sleeptime = qMin(tox_iteration_interval(tox), toxav_do_interval(toxav));
+    sleeptime = qMin(sleeptime, CoreFile::corefileIterationInterval());
+    toxTimer->start(sleeptime);
 }
 
 bool Core::checkConnection()
diff --git a/src/core/corefile.cpp b/src/core/corefile.cpp
index 744318f2f..41f805a3e 100644
--- a/src/core/corefile.cpp
+++ b/src/core/corefile.cpp
@@ -13,6 +13,25 @@ QMutex CoreFile::fileSendMutex;
 QHash<uint64_t, ToxFile> CoreFile::fileMap;
 using namespace std;
 
+unsigned CoreFile::corefileIterationInterval()
+{
+    /// Sleep at most 1000ms if we have no FT, 10 for user FTs, 50 for the rest (avatars, ...)
+    constexpr unsigned fastFileInterval=10, slowFileInterval=50, idleInterval=1000;
+    unsigned interval = idleInterval;
+
+    for (ToxFile& file : fileMap)
+    {
+        if (file.status == ToxFile::TRANSMITTING)
+        {
+            if (file.fileKind == TOX_FILE_KIND_DATA)
+                return fastFileInterval;
+            else
+                interval = slowFileInterval;
+        }
+    }
+    return interval;
+}
+
 void CoreFile::sendAvatarFile(Core* core, uint32_t friendId, const QByteArray& data)
 {
     QMutexLocker mlocker(&fileSendMutex);
diff --git a/src/core/corefile.h b/src/core/corefile.h
index 9588bb545..40539e8d3 100644
--- a/src/core/corefile.h
+++ b/src/core/corefile.h
@@ -24,6 +24,7 @@ class CoreFile
 private:
     CoreFile()=delete;
 
+    // Internal file sending APIs, used by Core. Public API in core.h
 private:
     static void sendFile(Core *core, uint32_t friendId, QString Filename, QString FilePath, long long filesize);
     static void sendAvatarFile(Core* core, uint32_t friendId, const QByteArray& data);
@@ -36,6 +37,9 @@ private:
     static ToxFile *findFile(uint32_t friendId, uint32_t fileId);
     static void addFile(uint32_t friendId, uint32_t fileId, const ToxFile& file);
     static void removeFile(uint32_t friendId, uint32_t fileId);
+    /// Returns the maximum amount of time in ms that Core should wait between two
+    /// tox_iterate calls to get good file transfer performances
+    static unsigned corefileIterationInterval();
 
 private:
     static void onFileReceiveCallback(Tox*, uint32_t friendnumber, uint32_t fileId, uint32_t kind,