Hallo ekki161 - danke für das Willkommen  ;-)
> keine Helferlein (soweit ich richtig verstehe)
> Avast 13.11 - immer up to date
> etliche Neustarts, Problem ist seit dem letzten Update permanent (auf meinen beiden iMacs tritt der Fehler nicht auf)
> ich sitze seit 30 Jahren an Macs - aber sowas hatte ich noch nie...
Hier der EtreCheck Report:
EtreCheck version: 5.1 (5020)
Report generated: 2018-12-10 23:05:12
Download EtreCheck from 
https://etrecheck.com
Runtime: 2:33
Performance: Excellent
Sandbox: Enabled
Full drive access: Disabled
Problem: Apps are crashing
Description: 
        Contacts App crashes immediately after start.
        Mouse reacts very slow sometimes.
Major Issues: None
Minor Issues:
    These issues do not need immediate attention but they may indicate future problems. 
    Clean up - There are orphan files that could be removed.
    Unsigned files - There are unsigned software files installed. They appear to be legitimate but should be reviewed.
    Limited drive access - More information may be available with Full Drive Access.
Hardware Information:
    Mac mini (Late 2014)
    Mac mini Model: Macmini7,1
    1 2,6 GHz Intel Core i5 (i5-4278U) CPU: 2-core
    16 GB RAM - Not upgradeable
    BANK 0/DIMM0 - 8 GB DDR3 1600 ok
    BANK 1/DIMM0 - 8 GB DDR3 1600 ok
Video Information:
    Intel Iris - VRAM: 1536 MB
    VX2263 Series 1920 x 1080
    PHL 243V5 1920 x 1080
Drives:
    disk0 - APPLE SSD SM0256G 251.00 GB (Solid State - TRIM: Yes)
    Internal PCI 5.0 GT/s x2 Serial ATA
        disk0s1 - EFI (MS-DOS FAT32) [EFI] 210 MB
        disk0s2 [APFS Container] 250.79 GB
            disk1 [APFS Virtual drive] 250.79 GB (Shared by 4 volumes)
                disk1s1 - Macintosh HD (APFS) (Shared - 88.83 GB used)
                disk1s2 - Preboot (APFS) [APFS Preboot] (Shared)
                disk1s3 - Recovery (APFS) [Recovery] (Shared)
                disk1s4 - VM (APFS) [APFS VM] (Shared - 20 KB used)
    disk2 - Samsung Portable SSD T5 2.00 TB
    External USB 5 Gbit/s USB
        disk2s1 - EFI (MS-DOS FAT32) [EFI] 210 MB
        disk2s2 - i************y (Mac OS Extended) 2.00 TB (970.27 GB used)
Mounted Volumes:
    disk1s1 - Macintosh HD 250.79 GB (161.27 GB free)
        APFS
        Mount point: /
    disk1s4 - VM [APFS VM] (Shared - 20 KB used)
        APFS
        Mount point: /private/var/vm
    disk2s2 - i************y 2.00 TB (1.03 TB free)
        Mac OS Extended
        Mount point: /Volumes/i************y
Network:
    Interface en0: Ethernet
    Interface en6: iPad
    Interface en5: iPhone
    Interface en4: Bluetooth PAN
    Interface bridge0: Thunderbolt Bridge
    Interface en1: Wi-Fi
System Software:
    macOS Mojave 10.14.1 (18B75) 
    Time since boot: About 13 hours
Security:
    GatekeeperEnabled
    System Integrity ProtectionEnabled
Unsigned Files:
    Launchd: /Library/LaunchAgents/com.avast.userinit.plist
        Executable: /Applications/Avast.app/Contents/Backend/hub/userinit.sh
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchDaemons/com.avast.update.plist
        Executable: /Applications/Avast.app/Contents/Backend/scripts/update/update.sh
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchDaemons/com.avast.init.plist
        Executable: /Applications/Avast.app/Contents/Backend/hub/init.sh
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchDaemons/com.avast.uninstall.plist
        Executable: /Library/Application Support/Avast/autouninstall/autouninstall.sh
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchAgents/org.macosforge.xquartz.startx.plist
        Executable: /opt/X11/libexec/launchd_startx /opt/X11/bin/startx -- /opt/X11/bin/Xquartz
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchDaemons/org.virtualbox.startup.plist
        Executable: /Library/Application Support/VirtualBox/LaunchDaemons/VirtualBoxStartup.sh restart
        Details: Exact match found in the whitelist - probably OK
    Launchd: /Library/LaunchDaemons/org.macosforge.xquartz.privileged_startx.plist
        Executable: /opt/X11/libexec/privileged_startx -d /opt/X11/lib/X11/xinit/privileged_startx.d
        Details: Exact match found in the whitelist - probably OK
Kernel Extensions:
    /Library/Application Support/VirtualBox
        VBoxDrv.kext (Oracle America, Inc., 5.2.18)
        VBoxNetAdp.kext (Oracle America, Inc., 5.2.18)
        VBoxNetFlt.kext (Oracle America, Inc., 5.2.18)
        VBoxUSB.kext (Oracle America, Inc., 5.2.18)
    /Library/Extensions
        FTDIKext.kext (Wacom Technology Corp., 1.0 - SDK 10.11)
    /System/Library/Extensions
        SamsungPortableSSDDriver.kext (Samsung Electronics, 1.5.02 - SDK 10.7)
        Wacom Tablet.kext (Wacom Technology Corp., Wacom Tablet 6.3.15-3 - SDK 10.11)
System Launch Agents:
    [Not Loaded] 16 Apple tasks
    [Loaded] 159 Apple tasks
    [Running] 124 Apple tasks
System Launch Daemons:
    [Not Loaded] 36 Apple tasks
    [Loaded] 184 Apple tasks
    [Running] 115 Apple tasks
    [Other] One Apple task
Launch Agents:
    [Loaded] com.avast.userinit.plist (? 4b9d47d7 - installed 2018-09-24)
    [Other] com.adobe.ARMDCHelper.cc24aef4a1b90ed56a725c38014c95072f92651fb65e1bf9c8e43c37a23d420d.plist (Adobe Systems, Inc. - installed 2018-02-15)
    [Loaded] org.macosforge.xquartz.startx.plist (? 8c13f787 - installed 2016-10-26)
    [Running] com.wacom.wacomtablet.plist (Wacom Technology Corp. - installed 2015-12-16)
Launch Daemons:
    [Loaded] com.adobe.fpsaud.plist (Adobe Systems, Inc. - installed 2018-11-29)
    [Loaded] org.macosforge.xquartz.privileged_startx.plist (? e9b47e8e - installed 2016-10-26)
    [Loaded] com.adobe.ARMDC.Communicator.plist (Adobe Systems, Inc. - installed 2018-02-15)
    [Not Loaded] org.virtualbox.startup.plist (? 700b9385 - installed 2018-09-18)
    [Running] com.wacom.TabletHelper.plist (Wacom Technology Corp. - installed 2016-10-11)
    [Loaded] com.avast.init.plist (? fe750b9b - installed 2018-09-24)
    [Loaded] com.avast.update.plist (? f4a2548f - installed 2018-09-24)
    [Loaded] com.apple.installer.osmessagetracing.plist (Apple - installed 2018-10-24)
    [Loaded] com.avast.uninstall.plist (? 1d68eef4 - installed 2018-09-24)
    [Loaded] com.wacom.displayhelper.plist (Apple - installed 2018-10-24)
    [Loaded] com.adobe.ARMDC.SMJobBlessHelper.plist (Adobe Systems, Inc. - installed 2018-02-15)
User Launch Agents:
    [Running] com.srib.pssddaemon.plist (Samsung Electronics - installed 2017-12-16)
    [Loaded] com.google.keystone.agent.plist (Google, Inc. - installed 2018-07-18)
Internet Plug-ins:
    FlashPlayer-10.6: 32.0.0.101 (installed 2018-12-06)
    QuickTime Plugin: 7.7.3 (installed 2018-11-21)
    AdobePDFViewerNPAPI: 17.012.20098 (installed 2018-10-23)
    AdobePDFViewer: 19.008.20080 (installed 2018-10-23)
    Flash Player: 32.0.0.101 (installed 2018-12-06)
    Silverlight: 5.1.50901.0 (installed 2018-07-22)
    WacomTabletPlugin: WacomTabletPlugin 2.1.0.6 (installed 2015-12-16)
3rd Party Preference Panes:
    Flash Player (installed 2018-11-29)
    WacomTablet (installed 2015-12-16)
Time Machine:
    Time Machine information not available without Full Drive Access.
Performance:
    System Load: 1.63 (1 min ago) 1.75 (5 min ago) 1.72 (15 min ago)
    Nominal I/O speed: 0.47 MB/s
    File system: 28.07 seconds
    Write speed: 716 MB/s
    Read speed: 751 MB/s
CPU Usage:
    Type Overall
    System 3 %
    User 6 %
    Idle 90 %
Top Processes by CPU:
    Process (count) CPU (Source - Location)
    Other processes 20.82 % (?)
    com.apple.WebKit.WebContent (6) 11.05 % (Apple)
    EtreCheck 4.12 % (App Store)
    Safari 1.26 % (Apple)
    com.apple.WebKit.Networking (3) 0.59 % (Apple)
Top Processes by Memory:
    Process (count) RAM usage (Source - Location)
    Safari 1.16 GB (Apple)
    EtreCheck 494 MB (App Store)
    Mail 298 MB (Apple)
    assistant_service 269 MB (Apple)
    com.apple.WebKit.WebContent (6) 266 MB (Apple)
Top Processes by Network Use:
    Process Input / Output (Source - Location)
    com.avast.proxy 208 MB / 1 MB (AVAST Software a.s.)
    mDNSResponder 570 KB / 265 KB (Apple)
    netbiosd 122 KB / 38 KB (Apple)
    apsd 21 KB / 65 KB (Apple)
    cloudd 20 KB / 9 KB (Apple)
Virtual Memory Information:
    Available RAM 5.62 GB
    Free RAM 14 MB
    Used RAM 10.38 GB
    Cached files 5.60 GB
    Swap Used 0 B
Software Installs (past 30 days):
    Install Date Name (Version)
    2018-11-11 Das Deutschlandradio (1.2.2)
    2018-11-11 Disk Speed Test (3.2)
    2018-11-11 Safari (12.0.1)
    2018-11-12 Numbers (5.0)
    2018-11-12 Pages (7.0)
    2018-11-12 Keynote (8.0)
    2018-12-06 Adobe Flash Player
    2018-12-06 Gatekeeper Configuration Data (157)
    2018-12-10 EtreCheck (5.1)
Clean up:
    /Applications/Avast.app/Contents/Backend/launch/com.avast.account-sync.plist
        @AV_BASE_DIR/utils/com.avast.account-sync
        Executable not found
Diagnostics Information (past 7 days):
    Directory /Library/Logs/DiagnosticReports is not accessible without Full Drive Access.
End of report