With Android Studio v3.5.2 on Ubuntu 18.04, the time elapsed between start and 'Welcome' window on my laptop was about 7...10 seconds. After upgrading to Ubuntu 19.10, same Android Studio has startup time about 25...30 seconds. No CPU or RAM usage spikes detected by System Monitor (2% and 10% accordingly). After 'Welcome' window everything works just fine. Here are log records:
2020-01-21 00:05:31,671 [49-5587405] INFO - #com.intellij.idea.Main - JVM Args: -Xms256m -Xmx1280m -XX:ReservedCodeCacheSize=240m -XX:+UseConcMarkSweepGC -XX:SoftRefLRUPolicyMSPerMB=50 -XX:CICompilerCount=2 -Dsun.io.useCanonCaches=false -Djava.net.preferIPv4Stack=true -Djdk.http.auth.tunneling.disabledSchemes="" -Djna.nosys=true -Djna.boot.library.path= -da -Dawt.useSystemAAFontSettings=lcd -Dsun.java2d.renderer=sun.java2d.marlin.MarlinRenderingEngine -Dsun.tools.attach.tmp.only=true -Xmx2048m -XX:ErrorFile=/home/user/java_error_in_STUDIO_%p.log -XX:HeapDumpPath=/home/user/java_error_in_STUDIO.hprof -Didea.paths.selector=AndroidStudio3.5 -Djb.vmOptionsFile=/snap/android-studio/81/android-studio/bin/studio64.vmoptions,/home/user/.AndroidStudio3.5/config/studio64.vmoptions -Didea.platform.prefix=AndroidStudio -Didea.jre.check=true
2020-01-21 00:05:31,671 [49-5587405] INFO - #com.intellij.idea.Main - ext: /snap/android-studio/81/android-studio/jre/jre/lib/ext: [cldrdata.jar, dnsns.jar, jaccess.jar, localedata.jar, meta-index, nashorn.jar, sunec.jar, sunjce_provider.jar, sunpkcs11.jar, zipfs.jar]
2020-01-21 00:05:31,671 [49-5587405] INFO - #com.intellij.idea.Main - charsets: JNU=UTF-8 file=UTF-8
2020-01-21 00:05:31,686 [49-5587405] INFO - #com.intellij.idea.Main - JNA library (64-bit) loaded in 14 ms
2020-01-21 00:05:56,931 [49-5587405] INFO - #com.intellij.util.ui.JBUI - System scale factor: 1.0 (IDE-managed HiDPI)
What causes 25 sec. delay between 'JNA library loaded' and 'System scale factor: 1.0'?
UPDATE (06 MAY 2020)
As for Ubuntu 19.10, after one of the automatic system updates the bug suddenly disappeared. Its cause remains unknown.