Address extensive memory usage

[ckittl]

Currently, there are several grid models, that consume a lot of memory:

• 1-HVMV-mixed-all-0-no_sw
• 1-HVMV-mixed-all-1-no_sw
• 1-HVMV-mixed-all-2-no_sw
• 1-HVMV-urban-all-0-no_sw
• 1-HVMV-urban-all-1-no_sw
• 1-HVMV-urban-all-2-no_sw
• 1-MVLV-comm-all-0-no_sw
• 1-MVLV-comm-all-1-no_sw
• 1-MVLV-comm-all-2-no_sw
• 1-MVLV-rural-all-0-no_sw
• 1-MVLV-rural-all-1-no_sw
• 1-MVLV-rural-all-2-no_sw
• 1-MVLV-semiurb-all-0-no_sw
• 1-MVLV-semiurb-all-1-no_sw
• 1-MVLV-semiurb-all-2-no_sw
• 1-MVLV-urban-all-0-no_sw
• 1-MVLV-urban-all-1-no_sw
• 1-MVLV-urban-all-2-no_sw

Try to address those cases.

[ckittl]

Most likely also addressed together with #19 in #71.