im try to open 4k video and my MPC very freezing!

Видео: 3840х2160p (16:9), 23.976 fps, AVC MPEG-4 (x265), High@L5.1 ~ 60.7 Mbps, 0.305 bit/pixel
Аудио#1: Русский 48 kHz, (AC3), 6ch, ~ 640 kbps [Профессиональный (полное дублирование) с Blu-ray CEE]
Аудио#2: Английский 48 kHz, DTS-HD Master Audio, 8ch, ~5460 kbps, 24-bit (DTS Core: 5.1 ch, 48 kHz, 1509 kbps, 24-bit) [Оригинал]

i am trying opening this video file from my externel HDD maybe thats why?

my pc is CPU amd fx 4300
ram 8gb
VGA EVGA 740GT 2 GB
WINDOWS 10

MPC-HC (Nightly, 64-bit)
------------------------

Build information:
Version: 1.7.10.269 (c1eba40)
Compiler: MSVC 2015 Update 3
Build date: Nov 16 2016

LAV Filters:
LAV Splitter: 0.68.1.53
LAV Video: 0.68.1.53
LAV Audio: 0.68.1.53
FFmpeg compiler: MinGW-w64 GCC 6.2.0

Operating system:
Name: Windows NT 10.0 (build 14393)
Version: 10.0 (64-bit)

Hardware:
CPU: AMD FX(tm)-4300 Quad-Core Processor
GPU: NVIDIA GeForce GT 740 (driver version: 21.21.13.6909)

Go to LAV Video decoder settings and enable "DXVA2 (native)" hardware acceleration.

That should fix the problem if the video is H.264/AVC (encoded by x264).
Your computer is not fast enough for H.265/HEVC (encoded by x265).

ok il try do this , but which PC i must to buy for optimum performance?

You could upgrade your GPU. For example a NVIDIA GTX 1050 has hardware acceleration for HEVC video.