Hello , 
I give up of kde4 desktop project because I have too much work and because I couldn't found a problem of performance.
After upgrade to F26 , 2 months ago , I see the issues remains more or less the same .

Today with my laptop with only 7 days of uptime , I suspend and wake it, 2 or 3 times a day .
I see plasmashell consuming 1.3 Gb of residual memory [1] . How I clear it without reboot laptop ?

Thanks

[1]
Process 1431 - plasmashell

Summary:

The process plasmashell (with pid 1431) is using approximately 1.3 GB of memory.
It is using 1.3 GB privately, 368.2 KB for pixmaps, and a further 32.5 MB that is, or could be, shared with other programs.
Dividing up the shared memory between all the processes sharing that memory we get a reduced shared memory usage of 8.5 MB. Adding that to the private and pixmap usage, we get the above mentioned total memory footprint of 1.3 GB.
46.9 MB is swapped out to disk, probably due to a low amount of available memory left.
Library Usage

The memory usage of a process is found by adding up the memory usage of each of its libraries, plus the process's own heap, stack and any other mappings, plus the stack of its 15 threads. 
Private
more
1384868 KB [heap]
2764 KB /usr/lib64/libQt5Qml.so.5.9.2
1316 KB /usr/lib64/libQt5Quick.so.5.9.2
732 KB /home/sergio/.cache/plasma_theme_F26_v26.0.kcache
440 KB /usr/bin/plasmashell
Shared
hide
6592 KB /home/sergio/.cache/ksycoca5_en_3DByexLmJRy1+LyB7kRxUFSA3pI=
3008 KB /home/sergio/.cache/ksycoca5_en_3DByexLmJRy1+LyB7kRxUFSA3pI= (deleted)
2852 KB /usr/lib64/libQt5Gui.so.5.9.2
2496 KB /usr/lib64/libQt5Core.so.5.9.2
1148 KB /usr/lib64/libQt5Quick.so.5.9.2
1076 KB /usr/lib64/libQt5Widgets.so.5.9.2
1056 KB /usr/lib64/dri/i965_dri.so
952 KB /usr/lib64/libc-2.25.so
712 KB /usr/lib64/libsqlite3.so.0.8.6
688 KB /usr/lib64/qt5/plugins/styles/oxygen.so
664 KB /usr/lib64/libKF5Solid.so.5.38.0
556 KB /usr/lib64/libKF5Service.so.5.38.0
528 KB /usr/lib64/libm-2.25.so
428 KB /usr/lib64/freetype-freeworld/libfreetype.so.6.13.0
408 KB /usr/lib64/libQt5XcbQpa.so.5.9.2
372 KB /usr/lib64/libKF5CoreAddons.so.5.38.0
320 KB /usr/lib64/libX11.so.6.3.0
312 KB /usr/lib64/libKF5XmlGui.so.5.38.0
304 KB /usr/lib64/libQt5DBus.so.5.9.2
272 KB /usr/lib64/libharfbuzz.so.0.10400.4
256 KB /usr/lib64/libKF5ConfigCore.so.5.38.0
252 KB /usr/lib64/libKF5Plasma.so.5.38.0
248 KB /usr/lib64/libKF5KIOFileWidgets.so.5.38.0
244 KB /usr/lib64/libKF5I18n.so.5.38.0
224 KB /usr/lib64/libpcre2-16.so.0.5.0
220 KB /usr/lib64/libKF5WindowSystem.so.5.38.0
204 KB /usr/lib64/libicuuc.so.57.1
200 KB /usr/lib64/libGLX_mesa.so.0.0.0
196 KB /home/sergio/.cache/icon-cache.kcache
192 KB /usr/lib64/libpng16.so.16.28.0
188 KB /usr/lib64/libKF5Notifications.so.5.38.0
188 KB /usr/lib64/libfontconfig.so.1.10.1
184 KB /usr/lib64/libpulse.so.0.20.2
180 KB /usr/lib64/libKF5KIOWidgets.so.5.38.0
176 KB /usr/lib64/libxkbcommon.so.0.0.0
168 KB /usr/lib64/libdbus-1.so.3.19.0
160 KB /usr/lib64/libKF5Bookmarks.so.5.38.0
160 KB /usr/share/fonts/dejavu/DejaVuSans.ttf
156 KB /usr/lib64/libQt5Qml.so.5.9.2
144 KB /usr/lib64/libKF5KIOCore.so.5.38.0
144 KB /usr/lib64/libQt5Xml.so.5.9.2
140 KB /usr/lib64/pulseaudio/libpulsecommon-11.1.so
136 KB /usr/lib64/libglib-2.0.so.0.5200.3
132 KB /usr/lib64/libKF5IconThemes.so.5.38.0
128 KB /usr/lib/locale/locale-archive
128 KB /usr/lib64/libudev.so.1.6.6
124 KB /usr/lib64/libKF5Activities.so.5.38.0
124 KB /usr/lib64/qt5/plugins/platformthemes/KDEPlasmaPlatformTheme.so
120 KB /usr/lib64/libKF5ConfigGui.so.5.38.0
116 KB /usr/lib64/libxcb.so.1.1.0
116 KB /usr/lib64/libKF5GlobalAccel.so.5.38.1
108 KB /usr/lib64/libglapi.so.0.0.0
100 KB /usr/lib64/libQt5Sql.so.5.9.2
96 KB /usr/lib64/libicudata.so.57.1
92 KB /usr/lib64/liboxygenstyle5.so.5.10.5
92 KB /usr/lib64/libprocesscore.so.5.10.5
92 KB /usr/lib64/libKF5GuiAddons.so.5.38.0
88 KB /usr/lib64/libz.so.1.2.11
80 KB /usr/lib64/libGLdispatch.so.0.0.0
76 KB /usr/lib64/libsystemd.so.0.18.0
76 KB /usr/share/mime/mime.cache
72 KB /usr/lib64/qt5/plugins/kf5/org.kde.kwindowsystem.platforms/KF5WindowSystemX11Plugin.so
64 KB /usr/lib64/qt5/qml/QtQuick/Controls/libqtquickcontrolsplugin.so
64 KB /usr/lib64/libQt5Svg.so.5.9.2
64 KB /usr/lib64/libxcb-xkb.so.1.0.0
64 KB /usr/lib64/libGLX.so.0.0.0
64 KB /usr/lib64/libGL.so.1.0.0
64 KB /usr/lib64/libIlmImf-2_2.so.22.0.0
64 KB /usr/lib/fontconfig/cache/12b26b760a24f8b4feb03ad48a333a72-le64.cache-7
64 KB /usr/lib64/libKF5WidgetsAddons.so.5.38.0
60 KB /usr/lib64/libKF5Package.so.5.38.0
60 KB /usr/lib64/libstdc++.so.6.0.24
60 KB /usr/lib64/libXi.so.6.1.0
60 KB /usr/lib64/libpthread-2.25.so
56 KB /usr/lib64/qt5/plugins/sqldrivers/libqsqlite.so
56 KB /usr/lib64/qt5/plugins/imageformats/kimg_xcf.so
52 KB /usr/lib64/libdrm.so.2.4.0
48 KB /usr/lib64/qt5/qml/org/kde/plasma/core/libcorebindingsplugin.so
48 KB /usr/lib64/libQt5PrintSupport.so.5.9.2
44 KB /usr/lib64/qt5/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so
44 KB /memfd:pulseaudio (deleted)
44 KB /usr/lib/fontconfig/cache/b79f3aaa7d385a141ab53ec885cc22a8-le64.cache-7
44 KB /usr/lib/fontconfig/cache/7b312f204090bff0956e0e66992a6837-le64.cache-7
40 KB /usr/lib64/ld-2.25.so
36 KB /usr/lib64/libXext.so.6.4.0
36 KB /usr/lib64/qt5/plugins/imageformats/kimg_eps.so
36 KB /usr/lib64/qt5/plugins/imageformats/libqjpeg.so
36 KB /usr/lib64/qt5/plugins/imageformats/libqicns.so
36 KB /usr/lib64/libKF5Style.so.5.38.0
36 KB /usr/lib64/libKF5Declarative.so.5.38.0
32 KB /usr/lib/fontconfig/cache/33315028185e8b9ecf55d3c7f93d9205-le64.cache-7
28 KB /usr/lib64/qt5/plugins/imageformats/kimg_rgb.so
28 KB /usr/lib64/qt5/plugins/imageformats/libqico.so
28 KB /usr/lib64/qt5/plugins/imageformats/libqgif.so
28 KB /usr/lib/fontconfig/cache/b67b32625a2bb51b023d3814a918f351-le64.cache-7
28 KB /usr/lib/fontconfig/cache/ceb0c0683e533aa11022c66e5c4d15df-le64.cache-7
24 KB /usr/lib64/qt5/plugins/kf5/org.kde.kidletime.platforms/KF5IdleTimeXcbPlugin0.so
24 KB /usr/lib64/qt5/plugins/imageformats/kimg_pic.so
24 KB /usr/lib64/qt5/plugins/imageformats/kimg_pcx.so
24 KB /usr/lib64/qt5/plugins/imageformats/libqtiff.so
24 KB /usr/lib/fontconfig/cache/92766a01268820036254e15fb956c917-le64.cache-7
20 KB /usr/lib64/libxcb-sync.so.1.0.0
20 KB /usr/lib64/qt5/plugins/imageformats/libqwebp.so
20 KB /usr/lib64/qt5/plugins/imageformats/libqsvg.so
20 KB /usr/lib64/qt5/plugins/imageformats/libqjp2.so
20 KB /usr/lib64/libxkbcommon-x11.so.0.0.0
20 KB /usr/lib64/libQt5WebChannel.so.5.9.2
20 KB /usr/lib/fontconfig/cache/3df8979866e8848a59fe99e84294e911-le64.cache-7
16 KB /usr/lib64/libKF5PlasmaQuick.so.5.38.0
16 KB /usr/lib64/qt5/plugins/xcbglintegrations/libqxcb-glx-integration.so
16 KB /usr/lib64/libxcb-xfixes.so.0.0.0
16 KB /usr/lib64/libKF5ConfigWidgets.so.5.38.0
16 KB /usr/lib64/qt5/plugins/imageformats/kimg_tga.so
16 KB /usr/lib64/qt5/plugins/imageformats/kimg_ras.so
16 KB /usr/lib64/qt5/plugins/imageformats/kimg_psd.so
16 KB /usr/lib64/qt5/plugins/imageformats/kimg_exr.so
16 KB /usr/lib64/qt5/plugins/imageformats/libqwbmp.so
16 KB /usr/lib64/qt5/plugins/imageformats/libqmng.so
16 KB /usr/lib64/libxcb-icccm.so.4.0.0
16 KB /usr/lib/fontconfig/cache/e3ead4b767b8819993a6fa3ae306afa9-le64.cache-7
12 KB /usr/lib64/libpulse-mainloop-glib.so.0.0.5
12 KB /usr/lib64/libxcb-shape.so.0.0.0
12 KB /usr/lib64/libQt5X11Extras.so.5.9.2
12 KB /usr/lib/fontconfig/cache/e26bf336397aae6fcef4d3803472adec-le64.cache-7
8 KB /usr/lib64/libxcb-composite.so.0.0.0
8 KB /usr/lib64/libxcb-present.so.0.0.0
8 KB /usr/lib64/libxcb-dri3.so.0.0.0
8 KB /memfd:xshmfence (deleted)
8 KB /usr/lib/fontconfig/cache/509acc703478ee028b2af3c265ded8f0-le64.cache-7
8 KB /usr/lib/fontconfig/cache/3f821257dd33660ba7bbb45c32deb84c-le64.cache-7
8 KB /usr/lib/fontconfig/cache/24519658f39a9a57c166fbf43ca6e79f-le64.cache-7
8 KB /usr/lib/fontconfig/cache/99a1ce9f8b6a0434aadb01d3779b0780-le64.cache-7
4 KB /usr/lib64/libKF5BluezQt.so.5.38.0
4 KB /usr/lib64/libxcb-damage.so.0.0.0
4 KB /usr/lib64/libxcb-shm.so.0.0.0
4 KB /usr/lib64/libxshmfence.so.1.0.0
4 KB /usr/lib/fontconfig/cache/54091e63ccbc9b283e4dea7ca32e5491-le64.cache-7
4 KB /usr/lib/fontconfig/cache/94cb2974bccbbbac26a4210e8676811e-le64.cache-7
4 KB /usr/lib/fontconfig/cache/06233d212212cb9148397f49821f92db-le64.cache-7
4 KB /usr/lib/fontconfig/cache/c37613e2604bdd41c402e32d2821e076-le64.cache-7
4 KB /usr/lib64/libX11-xcb.so.1.0.0
4 KB /usr/lib64/libgcc_s-7-20170915.so.1
4 KB /home/sergio/.local/share/mime/mime.cache
4 KB [vdso]
Sérgio M. B.