CCES working too slow in debug mode with ADSP BF707 using ICE-1000

Hi,
I have custom board with bf707 processor. It's required to receive some data from an external device on UART0 channel with using UART status interrupt handler.

Here is my UART configuration:

*pREG_UART0_CLK = 0x80000238; //115200 baud

*pREG_UART0_CTL = ADI_UART_ONE_STOPBIT|ADI_UART_WORDLEN_8BITS|ADI_UART_MODE_UART;
*pREG_UART0_CTL |= ENUM_UART_CTL_RX_IRQ_TH4;
*pREG_UART0_IMSK_SET |= BITM_UART_IMSK_SET_ERBFI|BITM_UART_IMSK_SET_ERFCI|BITM_UART_IMSK_SET_ERXS;
adi_int_InstallHandler(INTR_UART0_STAT,UART_RX0_ISR,0,true);
*pREG_UART0_CTL |= BITM_UART_CTL_EN;

and interrupt handler:

EX_HANDLER(INTR_UART0_STAT, UART_RX0_ISR)
{
uint8_t z = 0;
*pREG_PORTC_DATA_TGL |= BITM_PORT_FER_SET_PX14; //toggling FLG
z=*pREG_UART0_RBR;
//put z to FIFO
}

If my program boot from flash memory, then FLG pin is toggling synchronously on each received byte on and I see this process on oscilloscope.

But if I am using DEBUG mode and load program with EMU ICE-1000, then FLG starts toggling over 100-200ms after first byte on UART0_RX appear. UART_STAT.OE bit was already set in UART_RX0_ISR register.

If I load *.dxe with CCES_runner.exe, FLG toggling correctly.

Is it CCES trouble in emulation with ICE-1000?

My previous projects was build in Visual DSP and i haven't any problems with debug in emulation mode.

My PC configuration:
Inter core i7, 8GB, Windows 7 64-bit. Crosscore 2.7.0.0.