We present an optimized carrier recovery architecture based on differential detection for coherent optical receivers that substantially reduces the required DSP hardware resources, aimed to cost-effective transceivers for access networks applications. The proposed architecture shares the 1-symbol complex correlation required for differential phase detection within both the frequency estimation and the phase recovery blocks of the receiver DSP, thus lowering the energy consumption of the digital coherent receiver and increasing the tolerance against fast wavelength drifts of the lasers. We prototyped the proposed carrier recovery in a commercial FPGA for real-time evaluation with DPSK data at 1.25 Gb/s. The optical transmission system implemented direct-phase modulation of commercial DFB lasers, 25 km of single-mode fiber, and a coherent intradyne receiver with low-cost optical front-end based on 3x3 coupler and three photodiodes providing phase-diversity operation. Results show high performance in real-time for DPSK, achieving-55 dBm sensitivity at BER = 10-3 in a 6.25 GHz spaced ultra-dense WDM grid, high tolerance to optical phase noise, and enhanced mitigation of the fast wavelength drifts from lasers enabled by feed-forward DSP correction and feedback LO automatic tuning.