Mine is very smooth. There's no need to overclock, but at 1.2 GHz it's super smooth. Make sure you have the 27.10 build. To overclock go to Bootmenu, CPU settings, and set Clk4 to 1200 and Vsel4 to 60 or 62 or until it's stable (max 65). If you want you can also set Clk3 to 900. Select Save when done and reboot. It should be safe within Vsel 65.
Sent from my flying overclocked Motorola Defy+ MB526 with CyanogenMod 10 and custom kernel using XDA app
Motorola Defy+ MB526 - CyanogenMod 10 by Quarx 2ndboot (Android 4.1.2 Jelly Bean) - 1.2 GHz 8 GB Class 6 microSD
PC - Ubuntu 12.10 - Pentium 4 3.00 GHz - 1GB RAM - ATi Radeon HD 3650
Notebook - Ubuntu 13.04 - AMD Athlon 64 - 1GB RAM - ATi Radeon Xpress 200M
Old PC - Lubuntu 12.04 - AMD Athlon 1.1 GHz - 512 MB RAM - ATi Radeon 9250