Currently, gnome3 on F19 is bit problematic. If you use with BOINC manager GUI up, gnome-shell consumes excessive amount of CPU. There is several bug report for CPU utilization of gmome3 though, I can not be sure if one of them is addressiung this issue or not.

Please loot at the following top screen.
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top - 19:13:33 up 4 days, 5:16, 2 users, load average: 3.08, 2.43, 2.20
Tasks: 164 total, 3 running, 161 sleeping, 0 stopped, 0 zombie
%Cpu(s): 25.5 us, 1.2 sy, 73.0 ni, 0.0 id, 0.0 wa, 0.3 hi, 0.0 si, 0.0 st
KiB Mem: 6111680 total, 3423728 used, 2687952 free, 286124 buffers
KiB Swap: 6127612 total, 0 used, 6127612 free, 1561532 cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
20766 boinc 39 19 38048 36792 1120 R 79.8 0.6 0:06.26 wcgrid_sn2+
20660 boinc 39 19 467916 464732 1152 S 65.2 7.6 1:25.53 wcgrid_sn2+
1636 XXXXXXX 20 0 2239356 532452 47456 S 41.3 8.7 48:26.48 gnome-shell <= See here
991 root 20 0 290164 70896 12868 S 7.7 1.2 12:24.32 Xorg
20754 XXXXXXX 20 0 688792 32164 19848 S 3.7 0.5 0:02.42 boinc_gui
20561 boinc 39 19 2116 1260 896 S 0.7 0.0 0:06.03 wcgrid_sn2+
31 root 39 19 0 0 0 R 0.3 0.0 0:38.10 khugepaged
1240 boinc 30 10 462932 28584 6088 S 0.3 0.5 5:18.11 boinc_clie+
1676 XXXXXXX 20 0 236848 3620 2944 S 0.3 0.1 0:00.56 ibus-engin+
20541 boinc 39 19 2116 1260 896 S 0.3 0.0 0:10.03 wcgrid_sn2+
1 root 20 0 50992 7224 3544 S 0.0 0.1 0:02.24 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.06 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:01.72 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:+
7 root rt 0 0 0 0 S 0.0 0.0 0:00.05 migration/0
8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
9 root 20 0 0 0 0 S 0.0 0.0 0:11.74 rcu_sched
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This is not the peak but tipical with boinc_gui running on Core2-duo E8500 with 6MB RAM. You can see about 25% of CPU resource is used for graphic.
Only solution I can be sure is to stop BOINC Manager. Following is the top screen without BOINC Manager running.
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top - 19:09:44 up 4 days, 5:12, 2 users, load average: 2.09, 2.14, 2.09
Tasks: 161 total, 1 running, 160 sleeping, 0 stopped, 0 zombie
%Cpu(s): 2.0 us, 0.3 sy, 97.2 ni, 0.0 id, 0.0 wa, 0.3 hi, 0.2 si, 0.0 st
KiB Mem: 6111680 total, 3788604 used, 2323076 free, 286028 buffers
KiB Swap: 6127612 total, 0 used, 6127612 free, 1555096 cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
20653 boinc 39 19 468192 464992 1196 S 97.5 7.6 3:48.66 wcgrid_sn2+
20656 boinc 39 19 468076 464736 1144 S 96.8 7.6 2:33.02 wcgrid_sn2+
1636 XXXXXXX 20 0 2147056 495180 46808 S 3.3 8.1 47:35.13 gnome-shell
991 root 20 0 255492 65152 7736 S 0.7 1.1 12:11.40 Xorg
20541 boinc 39 19 2116 1260 896 S 0.7 0.0 0:09.09 wcgrid_sn2+
1240 boinc 30 10 462932 28584 6088 S 0.3 0.5 5:17.85 boinc_clie+
20561 boinc 39 19 2116 1260 896 S 0.3 0.0 0:05.08 wcgrid_sn2+
1 root 20 0 50992 7224 3544 S 0.0 0.1 0:02.23 systemd
2 root 20 0 0 0 0 S 0.0 0.0 0:00.06 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:01.72 ksoftirqd/0
5 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kworker/0:+
7 root rt 0 0 0 0 S 0.0 0.0 0:00.05 migration/0
8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 rcu_bh
9 root 20 0 0 0 0 S 0.0 0.0 0:11.73 rcu_sched
10 root rt 0 0 0 0 S 0.0 0.0 0:00.19 watchdog/0
11 root rt 0 0 0 0 S 0.0 0.0 0:00.19 watchdog/1
12 root rt 0 0 0 0 S 0.0 0.0 0:00.23 migration/1
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I found this issue after upgrading F18 to F19 with fedup. So, I do not know if gnome3 on prior to F18 acts the same way.

If any of you have any advice, I will appliciate. 'Cause I do not have enough time to pursue this issue by Japanese seasonal reason now, I am bringing up BOINC manager just when I need. Does any body has good solution for this issue?

P.S.
I already have installed latest update for fedora 19 with 'yum -y update' today.
Graphic is NVIDIA 7500GS.