file io - C# How should I save a large database of information? -

i wrote code serialize object containing data, save it, , load next time program run. (using binaryformater)

however program takes insanely long time load data (at 100 entrys, takes around 15-30 seconds), , need file store more @ around 300,000 entrys. save time isn't great either faster loading. i'd know sort of options there saving , loading database's , differences between them. have read xml pretty slow, know how lazy loading works (load needed), , file formats can applied to.

here code saves , repopulates data:

static void saveasbinary(string fullpath, object data)         {             // create new, empty data file.             string filename = fullpath;             if (file.exists(filename))             {                 console.writeline(filename + @" exists!");                 if (file.exists(filename + ".bak"))                 { file.delete(filename + ".bak"); }                 file.move(filename, filename + ".bak");             }             try             {                 binaryformatter bf = new binaryformatter();                 filestream fs = new filestream(filename, filemode.createnew);                 bf.serialize(fs, data);                 fs.flush(true);                 fs.dispose();             }             catch (exception ex)             {                 console.writeline("exception: " + ex.message);             }         }         private void populatedatabase(savedatabaseindex db)         {             if (last_page < cur_page) db.current_page = -1;             db.urllist = urllist;             db.firstentryonsave = firstentryonload;             foreach (string url in urllist)             {                 eh_entry ent = getentry(url);                 details_panesavedata detpane = new details_panesavedata                 {                     rating = ent.detailspanel.rating,                     uploader = ent.detailspanel.uploader,                     category = ent.detailspanel.category,                     date = ent.detailspanel.date,                     filecount = ent.detailspanel.filecount,                     filesize = ent.detailspanel.filesize,                     tags = ent.detailspanel.tags                 };                 eh_entrysave entsavedata = new eh_entrysave                 {                     dl_location = ent.dl_location,                     files = ent.file,                     title = ent.title,                     detail_savedata = detpane                 };                 db.eh_save.add(url, entsavedata);             }             saveasbinary(application.startuppath + "\\" + db.db_name + ".dat", db);         }         public void loaddatabase(string databasepath)         {             savedatabaseindex loadeddata = loadasbinary(databasepath) savedatabaseindex;             //populate required objects loaded data             if (loadeddata != null)             {                 cur_page = loadeddata.current_page;                 firstentryonload = loadeddata.firstentryonsave;                 urllist = loadeddata.urllist;                 parallel.foreach(urllist, enturl =>                 {                     eh_entrysave ent_save = loadeddata.eh_save[enturl] eh_entrysave;                     htentry.add(enturl, new eh_entry                     {                         detailspanel = new details_pane                         {                             rating = ent_save.detail_savedata.rating,                             uploader = ent_save.detail_savedata.uploader,                             category = ent_save.detail_savedata.category,                             date = ent_save.detail_savedata.date,                             filecount = ent_save.detail_savedata.filecount,                             filesize = ent_save.detail_savedata.filesize,                             tags = ent_save.detail_savedata.tags                         },                         dl_location = ent_save.dl_location,                         title = ent_save.title                     });                 });              }         }         static object loadasbinary(string fullpath)         {             string filename = fullpath;             if (file.exists(filename))             {                 try                 {                     filestream fs = new filestream(filename, filemode.open, fileaccess.read);                     binaryformatter bf = new binaryformatter();                     var loadeddata = bf.deserialize(fs);                     return loadeddata;                 }                 catch (exception ex)                 {                     console.writeline("exception: " + ex.message);                 }             }             else if (file.exists(filename + "bak"))                 filename = filename + "bak";                 try                 {                     filestream fs = new filestream(filename, filemode.open, fileaccess.read);                     binaryformatter bf = new binaryformatter();                     var loadeddata = bf.deserialize(fs);                     return loadeddata;                 }                 catch (exception ex)                 {                     console.writeline("exception: " + ex.message);                 }             }             return null;         } 

edit: clarify looking existing fileformat or db product use instead of using binary serialization.

edit2: question not worded great , ended finding answer problem here which database recommend use c# (.net) application?